Alcohol doesn't lower the effectiveness of most antibiotics. But it's still a good idea to avoid alcohol while taking antibiotics.
Antibiotics and alcohol can cause similar side effects, such as stomach upset, dizziness and drowsiness. Combining antibiotics and alcohol can increase these side effects.
A few antibiotics — such as metronidazole (Flagyl), tinidazole (Tindamax), and sulfamethoxazole and trimethoprim (Bactrim) — should not be mixed with alcohol because this may result in a more severe reaction. Drinking any amount of alcohol with these medications can result in side effects such as flushing, headache, nausea and vomiting, and rapid heart rate.
Also, the antibiotic linezolid (Zyvox) interacts with certain alcoholic beverages, including red wine and tap beer. Drinking these beverages with this medication can cause a dangerous increase in blood pressure.
Keep in mind that some cold medicines and mouthwashes also contain alcohol. So check the label and avoid such products while taking these antibiotics.
Although modest alcohol use doesn't reduce the effectiveness of most antibiotics, it can reduce your energy and delay how quickly you recover from illness. So, it's a good idea to avoid alcohol until you finish your antibiotics and are feeling better.