Side Effects of Bactrim

Bactrim is the brand name of a combination of the two antibiotic drugs trimethoprim and sulfamethoxazole. Some of the conditions it is used to treat are urinary tract and ear infections, especially in children, traveler's diarrhea and recurrent bronchitis. It's also used in the treatment and prevention of a form of pneumonia known as Pneumocystis carinii, especially in people with immune system weakness.

Common Side Effects

The most common side effects of Bactrim are nausea, vomiting, loss of appetite, rash, insomnia and joint pain. Some patients have developed allergies to trimethoprim or sulfamethoxazole. Patients are advised to inform their doctors if they develop signs of allergic reaction including hives, swollen tongue, lips or face and difficulty breathing.

Patients who have a history of allergic reaction to other sulfonamide drugs are advised to discuss this with their doctor before taking Bactrim.

Serious Side Effects

Rarely, some patients have developed the following diseases that were caused by severe allergic reactions to sulfamethoxazole that resulted in fatality: Stevens-Johnson syndrome, anaphylaxis, toxic epidermal necrolysis and aplastic anemia. Other possible serious side effects to Bactrim include bloody stool, severe stomach pain, blistering or peeling skin and urination problems.

Side Effects in Nursing Babies

Pregnant and nursing women are strongly advised not to take Bactrim. Sulfonamides such as sulfamethoxazole can pass into the placenta and breast milk. This can harm a nursing baby by causing a condition known as kernicterus, which is a form of brain damage caused by severe jaundice. Bactrim may also cause liver problems and anemia in babies.

Drug Interactions

Bactrim may decrease the efficacy of certain birth control pills, so backup contraception methods are advised while taking the drug. Taking Bactrim with the following drugs may increase the side effects of each medication: oral antidiabetics, methyldopa, valproic acid, sulfoxone, methenamine and Dilantin.

Warnings

Bactrim can cause increased sensitivity to sunlight resulting in sunburn. It is recommend that patients avoid sun exposure and tanning beds. Patients with AIDS who are taking Bactrim for Pneumocystis carinii pneumonia are likely to experience more side effects than patients without AIDS who have this pneumonia.

Chronic use of high doses of Bactrim can result in bone marrow depression and present as thrombocytopenia, leukopenia or megaloblastic anemia. Long-term use may also result in vaginal yeast infection or oral thrush.

Bactrim is not recommended for children under 2 months of age. It can also cause dizziness, and patients are advised to avoid operating heavy machinery if this happens.