While taking an antibacterial such as a cephalosporin or metronidazole, and for 7 days after stopping, do not drink alcohol, and do not take an alcohol-containing medicine such as Huoxiang Zhengqi oral liquid or cough syrup

Some cephalosporins, and drugs such as metronidazole, make the face flush and bring on sweating and a racing heart if they meet alcohol. A severe case brings trouble breathing and a drop in blood pressure. It is not only liquor and beer. An alcohol-containing medicine such as Huoxiang Zhengqi oral liquid (藿香正气水, a Chinese medicine liquid that contains alcohol) or cough syrup can do it too. Do not touch alcohol from the time you are taking the drug through 7 days after you stop.

Cost

No money. No alcohol for a little over a week. Before taking another medicine, glance at whether the ingredients include ethanol.

Benefit

This is called a disulfiram-like reaction. A 2023 medication-safety article from the Fujian drug regulator says that drinking before or after some cephalosporins can set off this reaction, and that it "can seriously harm health and can even threaten life." Symptoms include a flushed face, sweating, and palpitations, and even difficulty breathing, a drop in blood pressure, and anaphylactic shock. Following the Clinical Medication Notices of the Pharmacopoeia of the People's Republic of China, the drugs it lists include cefazolin, ceftriaxone, cefoperazone, metronidazole, tinidazole, and furazolidone, among others. It states that drinking alcohol, and taking or eating drugs or foods that contain alcohol, is forbidden for 7 days after the dose. The examples include liqueur chocolates and Huoxiang Zhengqi oral liquid. The reason given is that the enzyme the drug inhibits often takes 4 to 5 days to recover. A hospital in Guangzhou reviewed 82 cases over 2 years. Cephalosporins caused 57 cases (69.51%). Nitroimidazoles, the class that includes metronidazole and tinidazole, caused 10 cases (12.20%). The alcohol came from alcoholic drinks in 40 cases (48.78%) and from ethanol-containing medicines in 31 cases (37.80%). Medicines taken by mouth included Huoxiang Zhengqi oral liquid, cough syrup, and motherwort fluid extract (益母草流浸膏). Of the 82 cases, 68 were mild, 9 were moderate, and 5 were severe. They eased within 1 to 3 hours. Nobody died. The US leaflet for metronidazole requires no alcohol during treatment and for at least 3 days after stopping, and no products that contain propylene glycol.

Notes

Not every cephalosporin does this, but an ordinary person cannot tell them apart, so the simple course is to follow this rule for any of them. When a doctor prescribes a cephalosporin or metronidazole, say whether you drank in the past few days. That article also suggests not drinking for 3 days before the dose, and it admits that this gap has no authoritative statement at present. If the face flushes and the heart races, stop anything that contains alcohol at once. The article says a mild case can pass on its own, and a severe case needs a hospital. Do not drink alcohol while taking acetaminophen either. See item 1 of this section (acetaminophen). The grade is B because the evidence is a set of cases and a leaflet, with no comparison group. The benefit is rated small: all 82 cases eased within a few hours, nobody died, and only 5 were severe. For how to look after someone who is drunk, see section 13, item 46 (someone is drunk).

Sources · 3

1. 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. yjj.scjgj.fujian.gov.cn/ztzl/kpzl/qgaqyyy/202…
2. 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. doi.org/10.6039/j.issn.1001-0408.2015.29.19
3. Pfizer (2026). FLAGYL 375 (metronidazole) capsules, prescribing information: Contraindications, Interaction with Alcohol. DailyMed. dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?se…