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. https://yjj.scjgj.fujian.gov.cn/ztzl/kpzl/qgaqyyy/202312/t20231215_6334595.htm；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. https://doi.org/10.6039/j.issn.1001-0408.2015.29.19；Pfizer (2026). FLAGYL 375 (metronidazole) capsules, prescribing information: Contraindications, Interaction with Alcohol. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a2883ca1-5a9a-4259-9d80-46ab67274384
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.