[← Back to main index](../../README.md) # 34. Avoid serious harm from over-the-counter medicines at home Fever reducers, painkillers, cold remedies, stomach meds, and anti-diarrheal drugs — many of these can be bought without a prescription at any pharmacy. Just because they’re available without a doctor’s order doesn’t mean they can be taken carelessly. This section won’t list which medicine fits each condition; instead, it highlights a few simple actions that can prevent serious consequences. All figures here are based on mortality rates, covering outcomes such as liver failure, stomach bleeding, and newborn kidney failure. Most benefits boil down to “preventing at least one serious incident.” Since studies rarely quantify exactly how much risk drops after taking these steps, the benefit level is judged by how severe those possible outcomes would be — each entry explains the reasoning behind its rating. For topics already covered elsewhere, we simply point the way. If someone accidentally swallows medicine or cleaning products, see section 13, item 20 (accidental ingestion). For chronic-disease medicines taken as prescribed for the full course, see section 16, item 1 (finish the prescribed course). For buying prescription drugs online only after a prescription review, see section 28, item 6 (get weight-loss drugs with a hospital prescription). The beneficiaries of this section’s items are you and your family — the top two tiers. ### 1. Before taking two cold or pain relievers at the same time, check their ingredient lists — only one of them should contain acetaminophen - Cost: No cost at all. It only takes a minute or two to glance at the ingredient list on each package. - In plain terms: Acetaminophen is present in many cold medicines. Taking two such products means you’re consuming double the dose, which can damage the liver. In the U.S., nearly 30% of patients suffering from acute liver failure due to acetaminophen never receive a liver transplant in time. Domestic instructions recommend a maximum daily intake of 2 grams, and alcohol should be avoided while taking this drug. - Benefit: Over six years, 22 U.S. hospitals tracked 662 cases of acute liver failure. Of these, 275 (42%) were caused by acetaminophen; the median dose consumed was 24 grams. Among those 275 patients, 131 (48%) took the drug unintentionally. In 38% of those cases, they were also taking two or more other medications containing acetaminophen. Ultimately, 27% of these patients died before a transplant became possible, while 8% underwent liver transplantation. In 2020, China’s National Medical Products Administration mandated that OTC packaging clearly state excessive use can cause severe liver damage and that the daily limit is 2 grams. Packaging must also warn against combining this drug with other acetaminophen-containing or analgesic products. U.S. regulations require such OTC products to explicitly list three main risk factors: exceeding the daily limit, concurrent use with other acetaminophen-containing drugs, and drinking more than three alcoholic drinks daily while taking it. - Evidence grade: B - Sources:Larson AM, Polson J, Fontana RJ, et al.; Acute Liver Failure Study Group (2005). Acetaminophen-induced acute liver failure: results of a United States multicenter, prospective study. Hepatology, 42(6):1364-1372. ；国家药监局关于修订对乙酰氨基酚常释及缓释制剂说明书的公告（2020年第15号）及附件2《对乙酰氨基酚常释制剂非处方药说明书修订要求》（湖南省药品监督管理局转载）. ；21 CFR 201.326(a)(1)(iii)(A) Liver warning. - Notes: Acetaminophen is also known as paracetamol. Cold medicines whose generic names contain the characters “anfen” — such as paracetamol pseudoephedrine or paracetamol caffeine chlorpheniramine — all contain this ingredient. When in doubt, bring all your medications to a pharmacist for review. This evidence grade is set at B because the U.S. data comes from case registries lacking a control group, so it’s impossible to calculate exactly how many adverse events could be prevented by checking ingredient lists. The “large” benefit rating is based on the severity of outcomes: nearly 30% of acute liver failure cases end in death. ### 2. Do not give children aspirin, nimesulide, or metamizole for fever; cold medicines containing metamizole should also be avoided in minors - Cost: No cost involved. Simply check the generic name and ingredient list when buying fever reducers. - In plain terms: For reducing a child’s fever, none of these three drugs should be used. Aspirin is linked to Reye’s syndrome, a condition that damages the brain and liver; in U.S. statistics, around 30% of affected children died, though cases dropped by over 90% after warnings were issued. Nimesulide is prohibited for children under 12, while metamizole is banned for anyone under 18. - Benefit: Reye’s syndrome can lead to brain disease and fatty liver degeneration, typically occurring after influenza or chickenpox infections. Nationwide monitoring in the U.S. from 1981 to 1997 recorded 1,207 cases among children under 18; 82% of these had detectable salicic acid in their blood, a key component of aspirin-like drugs. The overall mortality rate was 31%. Warnings about salicylate-containing drugs began in 1980, when 555 cases were reported — the peak figure; since 1987, annual cases have stayed under 36. China’s drug regulator prohibited oral nimesulide formulations for children under 12 in 2011, and banned metamizole tablets for anyone under 18 in 2020. This ban also applies to compound Qinghao Metamizole Tablets, Chongganling Tablets, and Chongganling Capsules, all of which contain metamizole. - Evidence grade: B - Sources:Belay ED, Bresee JS, Holman RC, Khan AS, Shahriari A, Schonberger LB (1999). Reye's syndrome in the United States from 1981 through 1997. New England Journal of Medicine, 340(18):1377-1382. ；关于加强尼美舒利口服制剂使用管理的通知（国食药监安〔2011〕209号）. ；国家药监局关于修订安乃近相关品种说明书的公告（2020年第34号）及附件1至3. - Notes: Metamizole is not a first-choice treatment even for adults. Its package insert notes it may cause agranulocytosis, aplastic anemia, and anaphylactic shock, so it is only used short-term for severe conditions when no other effective drugs are available. Despite its name, Chongganling is not a regular cold medicine — it contains metamizole as well. For appropriate fever reducers and correct dosages based on body weight, consult a pediatrician or pharmacist. Infants under 3 months with a fever should be taken to a hospital immediately, as noted in Section 20, Item 8 (fever above 38°C requires immediate medical care). This B rating reflects that Reye’s syndrome statistics derive from monitoring reports, and the drop in cases after warnings is a correlative trend rather than evidence from controlled trials; the “significant benefit” rating is justified by the marked reduction in cases from 555 annually to under 36 after warnings were issued. ### 3. People over 60, with a history of stomach bleeding, taking anticoagulants or steroids should consult a doctor before using painkillers like ibuprofen - Cost: No cost involved. Simply ask a doctor or pharmacist. - In plain terms: Painkillers such as ibuprofen, naproxen, and aspirin can harm the stomach. In large-scale trials, individuals taking ibuprofen faced roughly four times the risk of stomach bleeding or perforation compared to those not taking it. This risk is even higher for older adults, those with prior stomach bleeding, individuals on anticoagulants or steroids, and regular drinkers. - Benefit: These medications are classified as nonsteroidal anti-inflammatory drugs (NSAIDs); common examples include ibuprofen, naproxen, and diclofenac. A meta-analysis encompassing 280 randomized trials involving 124,513 participants demonstrated that compared to placebo, ibuprofen raised the risk of upper gastrointestinal perforation, obstruction, or bleeding by an RR of 3.97 (95% CI 2.22–7.10; roughly fourfold). Naproxen showed an RR of 4.22 (2.71–6.56), while diclofenac resulted in an RR of 1.89 (1.16–3.09). All NSAIDs also approximately double the risk of heart failure. U.S. regulations mandate that over-the-counter NSAIDs carry warnings about stomach bleeding; these warnings specifically identify six high-risk groups: individuals over 60, those with prior stomach ulcers or bleeding, people on anticoagulants or steroids, individuals concurrently taking multiple NSAIDs, drinkers consuming more than three alcoholic beverages daily, and users exceeding recommended dosages or duration. - Evidence grade: A - Sources:Coxib and traditional NSAID Trialists' (CNT) Collaboration; Bhala N, Emberson J, Merhi A, et al. (2013). Vascular and upper gastrointestinal effects of non-steroidal anti-inflammatory drugs: meta-analyses of individual participant data from randomised trials. Lancet, 382(9894):769-779. ；21 CFR 201.326(a)(2)(iii)(A) Stomach bleeding warning. - Notes: The study conclusions pertain to high-dose usage. No separate figures are provided for occasional short-term use at standard doses. Many multi-ingredient cold remedies also contain NSAIDs; combining them with separate painkillers results in redundant intake. Patients prescribed low-dose aspirin long-term by physicians for thrombosis prevention must not discontinue it or self-administer additional NSAIDs without medical guidance. ### 4. For children under 2 with colds, don’t give them over-the-counter multi-ingredient cold and cough medicines on your own - Cost: There is no cost at all; you even save money by not buying these medicines. - In plain terms: China’s National Medical Products Administration requires 14 types of over-the-counter multi-ingredient cold medicines for children to carry a warning label stating they are not recommended for parents to give to kids under 2 years old, and should only be used under the guidance of a doctor or pharmacist. Clinical trials conducted on children show that cough medicines and antihistamines have no better effect than placebo. - Benefit: In its Announcement No. 57 of 2021, the National Medical Products Administration updated the instructions for 14 such medicines, including paracetamol, pseudoephedrine and dextromethorphan oral solution, pediatric paracetamol, artificial cow-bezoar and chlorpheniramine maleate granules, and pediatric paracetamol and amantadine hydrochloride granules. The new warning reads: “It is not recommended for parents or guardians to give these products to infants under 2 years old on their own; they should only be used under the guidance of a doctor or pharmacist.” An additional note was added: “These products must be used strictly according to the dosage instructions on the package to avoid overdosing.” Another note states: “Concurrent use of other cold medicines containing the same or similar active ingredients should be avoided.” A Cochrane systematic review included 29 randomized controlled trials, 10 of which were conducted on children. For all these medicine types, no better effect than placebo was observed in pediatric trials: cough medicines, antihistamines (the anti-allergy component), antihistamines combined with decongestants (the ingredient that relieves nasal congestion), and cough medicines combined with bronchodilators. Adverse reactions were reported in 21 studies, with formulations containing antihistamines and dextromethorphan showing a higher incidence of side effects. - Evidence grade: B - Sources:国家药监局关于修订氨酚麻美口服溶液等14个品种药品说明书的公告（2021年第57号）及附件. ；Smith SM, Schroeder K, Fahey T (2014). Over-the-counter (OTC) medications for acute cough in children and adults in community settings. Cochrane Database of Systematic Reviews, (11):CD001831. - Notes: Many of these 14 medicines have “paracetamol” in their name, as they contain acetaminophen. Taking them together with other fever reducers will lead to redundant intake, as noted in Section 1 of this chapter (on acetaminophen). One trial included in the review found honey to be more effective than placebo for treating coughs, but honey should not be given to children under 1 year old, as detailed in Section 20, Item 6 (on honey). The evidence grade is set to B because there are very few trials for each type of medicine in the review, and the authors could not calculate a combined statistical figure. The benefit level is rated “moderate” as there is no proven benefit of these medicines for children, while the main risks are overdosing and redundant intake of similar active ingredients. ### 5. Pregnancy after 20 weeks: avoid taking ibuprofen and similar painkillers on your own - Cost: No cost involved. - In plain terms: After 20 weeks of pregnancy, most of the amniotic fluid is produced by the fetus’s kidneys. Taking ibuprofen or similar medications at this stage may harm the fetal kidneys and reduce the amount of amniotic fluid. Some reports received by U.S. authorities describe cases where newborns died after such exposure. Low-dose aspirin prescribed by doctors is not included in this warning. - Benefit: In October 2020, the U.S. Food and Drug Administration (FDA) issued a safety warning. Use of nonsteroidal anti-inflammatory drugs after roughly 20 weeks of pregnancy may cause kidney problems in the fetus, leading to low amniotic fluid levels. This warning applies to both prescription and over-the-counter drugs, including aspirin, ibuprofen, naproxen, diclofenac and celecoxib. After reviewing adverse event reports up to July 2017, the FDA identified 35 cases of low amniotic fluid or neonatal kidney dysfunction, all with serious outcomes; 5 of these newborns died, each with accompanying kidney failure. In most documented cases, amniotic fluid levels returned to normal within 72 hours to 6 days after medication use stopped. The FDA advises pregnant women not to take these drugs after week 20 unless explicitly directed by a doctor. Low-dose aspirin (81 mg) prescribed for specific pregnancy-related conditions is exempt from this restriction. When pain relief or fever reduction is needed, the FDA recommends using alternatives such as acetaminophen; consult a pharmacist or doctor first. - Evidence grade: B - Sources:U.S. Food and Drug Administration (2020-10-15). FDA recommends avoiding use of NSAIDs in pregnancy at 20 weeks or later because they can result in low amniotic fluid. Drug Safety Communication. - Notes: The FDA notes that many over-the-counter products for colds, flu or insomnia also contain these ingredients, so always check the ingredient list. Previously, U.S. over-the-counter drug labels only warned against use in the final 3 months of pregnancy; this new warning sets the cutoff at around 20 weeks. Low-dose aspirin for preventing preeclampsia is discussed in Section 27, point 5 (“Low-dose aspirin”). The grade B rating reflects that these figures come from adverse event reports; we have no data on how many women took these drugs without experiencing any issues. The “moderate” benefit rating reflects the seriousness of these outcomes, even though they occur infrequently. ### 6. Buying omeprazole over the counter for heartburn and acid reflux — use it for no more than 7 days; see a doctor immediately if you have trouble swallowing, vomit blood, or pass black stools - Cost: No cost involved — just follow the dosage instructions on the package. - In plain terms: Since 2022, omeprazole enteric-coated tablets have been available over the counter without a prescription. However, the package instructions clearly state that you should only take it for up to 7 days, and avoid using it again within two months. If you experience trouble swallowing, pain in the throat, vomit blood, or pass black stools, do not take it on your own — these are potential signs of serious medical conditions. This medication can also mask symptoms of stomach cancer, potentially delaying an accurate diagnosis. - Benefit: In its Announcement No. 68 of 2022, the National Medical Products Administration reclassified omeprazole enteric-coated tablets from a prescription drug to an over-the-counter medication, and released a standard package insert for it. The approved indication listed in the insert is “short-term relief of heartburn and acid reflux caused by excess stomach acid”. The precautions section specifies that the drug must not be used for more than 7 days, and that patients should consult a physician or pharmacist if symptoms persist. It also states that the drug must not be taken again within two months, and that immediate medical attention is required if symptoms recur. Use is prohibited if a patient has trouble swallowing, throat pain, vomit blood, or passes black stools, as these are possible indicators of serious illness. For patients showing warning signs such as unexplained weight loss, repeated vomiting, trouble swallowing, vomit blood, or black stools, malignant tumors must be ruled out first, since treatment with this drug may conceal symptoms and delay diagnosis. Patients over 55 years old with new or changing symptoms should consult a doctor before use. People taking clopidogrel must avoid taking omeprazole at the same time. - Evidence grade: B - Sources:国家药监局关于奥美拉唑肠溶片处方药转换为非处方药的公告（2022年第68号）及附件2《非处方药说明书范本》. - Notes: Clopidogrel is a blood-thinning medication commonly prescribed to patients who have had a stent implanted or a myocardial infarction. Omeprazole can reduce its effectiveness, so patients taking clopidogrel must consult a doctor first. The evidence grade is set to B because these requirements are stipulated in the official package insert, and no research has been conducted to quantify how many adverse events can be prevented by following these instructions. The benefit level is rated “moderate” because while this medication helps prevent delayed diagnosis of stomach bleeding or stomach cancer, most cases of heartburn and acid reflux are not severe. ### 7. Don’t ask doctors for antibiotics for the common cold - Cost: It costs nothing and can even save you money on medicine. - In plain terms: Taking antibiotics for a cold doesn’t speed up recovery compared to not taking them at all. For adults, the risk of side effects is more than twice as high when using antibiotics. For cases where nasal discharge with pus lasts less than 10 days, there is no clear benefit to taking antibiotics either. - Benefit: A Cochrane systematic review pooled data from 6 randomized trials involving 1,147 participants. When comparing antibiotic use to placebo for treating colds, there was no significant difference in the proportion of people who did not recover or whose symptoms persisted (RR 0.83, 95% CI 0.60–1.14, no statistically significant difference). The risk of adverse reactions was 1.8 times higher than in the placebo group (95% CI 1.01–3.21). For adults specifically, this risk was 2.62 times higher (1.32–5.18), while no increase was observed in children (RR 0.91, 0.51–1.63). For acute purulent rhinitis where nasal discharge with pus lasts less than 10 days, antibiotics also showed no clear benefit (RR 0.73, 0.47–1.13). However, the risk of adverse reactions rose by roughly 46% (RR 1.46, 1.10–1.94). The authors concluded that routine use of antibiotics is not recommended for either of these conditions. - Evidence grade: A - Sources:Kenealy T, Arroll B (2025). Antibiotics for the common cold and acute purulent rhinitis. Cochrane Database of Systematic Reviews, 11:CD000247. - Notes: This updated version was released in 2025; the abstract states that literature searches were conducted up to 2013. Antibiotics are prescription-only drugs in China, so pharmacies must sell them only with a valid prescription. Do not take leftover antibiotics at home without medical advice. The “moderate” rating for benefits is based on the fact that antibiotics primarily reduce the risk of adverse reactions rather than preventing death. ### 8. For diarrhea, start by drinking oral rehydration solution; do not give anti-diarrheal drugs to children under 5 - Cost: A box of oral rehydration solution costs just a few dollars, so it’s worth keeping one at home. - In plain terms: The most important thing during diarrhea is rehydration, not stopping the diarrhea itself. Mix the solution exactly as directed on the package and drink it — never substitute it with sugary juices or soft drinks, as the excess sugar can actually worsen dehydration. Never give anti-diarrheal medications such as loperamide to kids under 5 years old; in severe cases these drugs can cause life-threatening intestinal blockages. - Benefit: WHO’s guidelines on diarrhea treatment state clearly that anti-diarrheal and anti-vomiting drugs provide no real benefit for children with acute or prolonged diarrhea. They do not prevent dehydration or improve nutritional status, and some carry serious, even fatal side effects — so they must never be given to children under 5. Drugs like loperamide that slow intestinal motility can lead to severe paralytic intestinal obstruction, which is potentially fatal and can prolong the underlying infection. The same guidelines also warn that drinks high in sugar draw water into the intestines, causing hypernatremic dehydration; this applies to soft drinks and most commercially sold fruit juices. WHO recommends a low-osmolarity formula with a total osmotic pressure of 245 mOsm/L; compared to older formulations, this reduces unplanned intravenous fluid administration by 33%. A Cochrane review of 8 trials reached similar conclusions (OR 0.59, 95% CI 0.45–0.79), showing roughly a 40% reduction in complications when this solution is used. - Evidence grade: A - Sources:World Health Organization (2005). The treatment of diarrhoea: a manual for physicians and other senior health workers, 4th revision. ；Hahn S, Kim S, Garner P (2002). Reduced osmolarity oral rehydration solution for treating dehydration caused by acute diarrhoea in children. Cochrane Database of Systematic Reviews, (1):CD002847. - Notes: When purchasing oral rehydration solution, always check the package label for its osmotic pressure and choose the low-osmolarity version. The WHO guidelines also note that blood in a child’s stool almost always indicates bacterial dysentery, which requires medical treatment with antibiotics — rehydration alone is not sufficient. The “moderate” benefit rating here reflects the fact that the available data compares two different rehydration solutions rather than the effect of drinking any solution versus none. ### 9. Don’t take painkillers for more than 15 days a month; limit combination painkillers to 10 days. Otherwise, headaches may actually be caused by the medication itself - Cost: No direct cost. You’ll just need to keep track of how many days you’ve taken the medicine, and resist the urge to pop pills at every sign of a headache. - In plain terms: If you suffer from frequent headaches and take painkillers every day, you might end up with even more frequent headaches. The International Classification of Headache classifies this condition as medication-overuse headache. For regular non-opioid painkillers like acetaminophen, aspirin and ibuprofen, taking them for 15 days or more per month for 3 consecutive months meets the criteria. For combination painkillers — which contain two or more pain-relieving ingredients or extra additives like caffeine (for example, acetaminophen with codeine) — the limit is 10 days per month over the same period. Even if you rotate between different non-opioid painkillers, the total number of days you take them still counts toward this limit. Epidemiological studies from multiple countries confirm that over half of people who experience headaches for 15 days or more each month fall into this category. Most patients see their symptoms improve after cutting back on excess medication, and other preventive headache treatments also become more effective. - Benefit: The third edition of the International Classification of Headache published by the International Headache Society outlines the diagnostic criteria for this condition. It applies to people who already have a history of headaches, experience headaches on 15 or more days each month, and have been regularly taking excessive amounts of headache medication for over 3 months. For standard non-opioid painkillers, the threshold for overuse is 15 days per month; for combination painkillers, it is 10 days per month. This classification is backed by robust epidemiological evidence, and most patients see positive results after reducing their medication intake. - Evidence grade: B - Sources:Headache Classification Committee of the International Headache Society (2018). The International Classification of Headache Disorders, 3rd edition. Cephalalgia, 38(1):1-211. ；ICHD-3 在线版 8.2 Medication-overuse headache（含 8.2.3、8.2.5）. - Notes: Painkillers with “caffeine” in their name typically contain added caffeine, so they count toward the 10-day limit for combination painkillers. If you find that your headache days are increasing month on month, it’s best to consult a neurologist rather than simply taking more medication. This evidence grade is assigned because the classification criteria serve as a diagnostic benchmark rather than being derived from controlled clinical trials. The benefit level is rated “moderate” as it primarily reduces the frequency of headaches without preventing life-threatening outcomes. ### 10. Clear out expired and unused medicines regularly; dispose of them with packaging in hazardous-waste bins, not at home - Cost: No cost. Sort the medicine cabinet once a year — about ten minutes. - In plain terms: Nearly half of unsupervised pediatric medication ingestions involve prescription tablets. About three in ten of those prescriptions belong to grandparents. Removing unused drugs removes one thing a child can find. Put discarded medicines in hazardous-waste bins with original packaging, or hand them to pharmacies that collect old drugs. - Benefit: U.S. emergency-department surveillance estimated that from 2004 to 2013, children under 6 took medicines without adult supervision about 640,000 times (estimate 640,161 ED visits). In 2013 alone about 59,000 visits (59,092). From 2010 to 2013 the most common form was oral prescription tablets, 45.9% of cases. Among prescriptions, opioids (13.8%) and benzodiazepines (12.7%) were most common. In 2017 five U.S. poison centers surveyed callers: for prescription ingestions, 30.7% involved grandparents’ medicines. More than half (51.5%) of prescription drugs had been removed from original packaging before the child accessed them. China’s National Catalogue of Hazardous Wastes (2025 edition) classifies household discarded medicines and their packaging as hazardous waste in domestic refuse. Shanghai’s sorting guide puts waste medicines in hazardous waste, including expired drugs, capsules, tablets, and inner packaging — “discard medicines preferably with packaging.” Shanghai also requires pharmacies collecting household expired medicines to use temporary transfer points set by district market-supervision departments. The U.S. FDA states the best disposal for expired and unwanted medicines is take-back programs. - Evidence grade: B - Sources:Lovegrove MC, Weidle NJ, Budnitz DS (2015). Trends in Emergency Department Visits for Unsupervised Pediatric Medication Exposures, 2004-2013. Pediatrics, 136(4):e821-e829. ；Agarwal M, Lovegrove MC, Geller RJ, et al. (2020). Circumstances Involved in Unsupervised Solid Dose Medication Exposures among Young Children. Journal of Pediatrics, 219:188-195.e6. ；生态环境部等 (2024). 国家危险废物名录（2025年版），附录《危险废物豁免管理清单》第 1 项. ；上海市绿化和市容管理局 (2024). 上海市生活垃圾分类投放指引（2024版）（沪绿容〔2024〕278号）. ；上海市绿化和市容管理局、上海市环境保护局、上海市食品药品监督管理局 (2018). 关于规范生活垃圾分类有害垃圾全程管理的通知. ；U.S. Food and Drug Administration (2025). Where and How to Dispose of Unused Medicines. - Notes: Local waste-sorting rules differ; follow the directory posted at your building’s waste room. In Shanghai, traditional Chinese medicine dregs go in wet waste, not hazardous. Keep remaining drugs in original boxes, not pill organizers or other bottles, out of children’s reach — see Section 13, item 20 (accidental ingestion). Do not self-treat with leftover antibiotics — item 7 in this section. When no U.S. take-back exists, FDA allows mixing with coffee grounds or cat litter before sealing in trash; a few strong painkillers may be flushed — that is U.S. practice; in China follow local sorting. Rated B because U.S. figures are registry counts without studies on how much cabinet cleanouts reduce ingestions. Benefit rated small: numbers are ED visits, not deaths, and the effect of cleaning cannot be calculated from them. ### 11. While taking cephalosporins, metronidazole, and similar antibacterials, and for 7 days after stopping, avoid alcohol — including alcohol in Huoxiang Zhengqi oral liquid and cough syrups - Cost: No money. Abstain from alcohol for a little over a week; check other medicines for ethanol on the label. - In plain terms: Some cephalosporins and metronidazole can trigger flushing, palpitations, chest tightness, and vomiting when mixed with alcohol; severe cases drop blood pressure. Beer and spirits are not the only triggers — Huoxiang Zhengqi oral liquid and cough syrups with alcohol count. Avoid alcohol from the start of the drug through 7 days after the last dose. - Benefit: This is a disulfiram-like reaction. A 2023 medication-safety popularization from the Fujian Provincial Medical Products Administration states that drinking before or after some cephalosporins may trigger this reaction, “which can seriously harm health or be life-threatening.” Symptoms include facial flushing, sweating, palpitations, even dyspnea, hypotension, and anaphylactic shock. Citing the Chinese Pharmacopoeia Clinical Medication Information, listed drugs include cefazolin, ceftriaxone, cefoperazone, metronidazole, tinidazole, furazolidone, and others. The article states “no alcohol or alcohol-containing drugs or foods for 7 days after dosing,” examples including liqueur chocolates and Huoxiang Zhengqi oral liquid, because the inhibited enzyme often needs 4 to 5 days to recover. One Guangzhou hospital summarized 82 cases over 2 years: cephalosporins caused 57 cases (69.51%), nitroimidazoles (metronidazole, tinidazole) 10 cases (12.20%). Alcohol from beverages 40 cases (48.78%), from ethanol-containing medicines 31 cases (37.80%) — including Huoxiang Zhengqi oral liquid, cough syrup, and motherwort extract. Of 82 cases, 68 mild, 9 moderate, 5 severe; relief within 1–3 hours; no deaths. U.S. metronidazole labeling requires no alcohol during treatment and for at least 3 days after, and no products containing propylene glycol. - Evidence grade: B - Sources:福建省药品监督管理局（福建省药品科普与监管数据中心）(2023). 2023年“全国安全用药月”原创科普小知识——为什么吃头孢不能喝酒. ；房财富, 涂星, 刘韬, 黄红兵, 邱孟, 梁蔚婷 (2015). 我院双硫仑样反应82例分析. 中国药房, 26(29):4089-4091. ；Pfizer (2026). FLAGYL 375 (metronidazole) capsules, prescribing information: Contraindications, Interaction with Alcohol. DailyMed. - Notes: Not every cephalosporin reacts, but laypeople cannot tell them apart — follow this rule for any cephalosporin or metronidazole course. Tell the doctor if you drank recently when these are prescribed. The popularization also suggests avoiding alcohol for 3 days before dosing while noting no authoritative interval. If flushing or palpitations start, stop all alcohol immediately; mild cases may resolve on their own, severe cases need hospital care. Do not drink alcohol while taking acetaminophen — item 1 in this section. Rated B because evidence is case series and labeling, not controlled trials. Benefit rated small: all 82 cases recovered within hours, no deaths, only 5 severe.