Sulfamethoxazole Trimethoprim Side Effects

Possible side effects of sulfamethoxazole and trimethoprim are listed below. Call your doctor for medical advice if they are severe or persistent:

• Nausea
• Vomiting
• Stomach ache
• Loss of appetite

Sulfamethoxazole and trimethoprim can also cause more serious side effects in some people. Call your doctor right away or seek emergency medical help if you develop the following serious symptoms:

• Signs of an allergic reaction (skin rash, hives, itching)
• Flu-like symptoms (fever, chills, sore throat, unusual tiredness)
• Severe diarrhea (watery or bloody stools) with or without stomach cramps and fever (this can happen up to 2 months or more after finishing antibiotic treatment)
• Cough
• Shortness of breath
• Chest pain
• Yellowing of the skin or eyes
• Unusual bruising or bleeding
• Pale skin
• Purple or red skin discoloration
• Joint pain
• Muscle pain

The above list may not include all the potential side effects of sulfamethoxazole and trimethoprim. Contact your healthcare provider if your side effects are unusual or severe or if they do not get better over time. You can also report suspected adverse reactions to the Food and Drug Administration at 1-800-FDA-1088.

Sulfamethoxazole and trimethoprim Overdose: In case of an overdose of sulfamethoxazole and trimethoprim, call your doctor immediately. You can also call your local poison control center or the national poison control center at 1-800-222-1222. Call 911 if a person has trouble breathing, has collapsed, is unresponsive, or has had a seizure. 

Treatment for an overdose consists of gastric lavage or emesis (vomiting), oral fluids, or intravenous fluids if there is low urine output and normal renal function. Acidifying the urine helps in the renal clearance of the trimethoprim component. Monitoring of blood counts and blood chemistries, including electrolytes, is also recommended. Additionally, complications such as blood dyscrasia or jaundice are treated if present. Hemodialysis may need to be done to eliminate sulfamethoxazole and trimethoprim from the body.

Source: FDA