Side Effects of Mixing Bactrim With Alcohol

Bactrim is the brand name of a formulation containing sulfamethoxazole and trimethoprim. Other brand names for similar formulations include Cotrim, Septra, Sulfamethoprim, Sulfatrim, and TMP-SMZ. The following information applies to all of these formulations.

Bactrim is an antibiotic drug used to treat bacterial infections. It is commonly prescribed for urinary tract infections, ear infections, and chronic bronchitis, as well as traveler's diarrhea, cholera, Pneumocystis carinii pneumonia (PCP), nocardiosis (a type of lung infection), prostate infections, and Salmonella infection.

Bactrim works by interfering with infectious bacteria's ability to use folic acid. It works in two different ways, making it a more efficient antibiotic than some others.

Certain people should not take Bactrim, including people with folic-acid deficiency, infants under age 2 months, and nursing mothers. Pregnant women should use caution before taking this product; if they are nearing delivery, they should not use Bactrim because it could be dangerous for the baby. Earlier in the pregnancy, Bactrim's effect on folic acid — needed for normal development in the fetus — may cause it to be contraindicated.

People who are allergic to certain drugs — sulfa drugs, diabetes drugs, and thiazide diuretics — should not take Bactrim because of the chance of a potentially fatal allergic reaction.

People with liver or kidney disease should be careful using Bactrim. Bactrim can affect the kidneys and decrease urine output.

Potential side effects of Bactrim include the following:

• Nausea, vomiting, upset stomach, diarrhea, loss of appetite
• Fever, chills
• Cough
• Sensitivity to sunlight
• Rash, itching

Less common side effects include reduced blood counts, neurological symptoms, eye swelling, coating of the tongue, pain similar to arthritis, and fatigue.

People taking bactrim should not drink alcohol during treatment. This includes not only alcoholic beverages, but cough medicines and mouthwash containing alcohol. The reason is that alcohol can intensify the negative side effects of Bactrim. When these two are combined, the result can be alarming and even dangerous symptoms: headache, nausea, vomiting, rapid heart rate (tachycardia), and shortness of breath. Nausea and vomiting can cause dehydration, and vomiting up the medicine results in a missed dose.

If you have a history of alcoholism, use Bactrim with caution, especially if your drinking is not under control.

Alcohol does not reduce the effectiveness of Bactrim, so if you drank alcohol during treatment, you do not need to worry that the treatment was compromised or made ineffective, unless you vomited a dose. However, you should not drink any more alcohol until the treatment is completed.

• The Pill Book, 12th Edition, 2006. Harold M. Silverman, Pharm. D., Editor-in-Chief. New York: Bantam Books.
• James M. Steckelberg, M.D. "Antibiotics and alcohol: Should I avoid mixing them?" 2008, MayoClinic.com.