List of side effects of trimethoprim/sulfamethoxazole

Adverse effects by incidence of trimethoprim/sulfamethoxazole ^{[1][2][3][4][5][6][7]}

Common (>1% frequency)

• Fever
• Nausea
• Vomiting
• Diarrhea
• Weight loss
• Rash
• Muscle aches
• Joint pain
• Itch
• Sore mouth
• Hyperkalaemia (high blood potassium)
• Thrombocytopenia (low number of platelets in the blood)

Infrequently (0.1–1.0% frequency)

• Headache
• Jaundice
• Elevated liver transaminases
• Peripheral neuritis
• Drowsiness
• Constipation
• Photosensitivity (light sensitivity)
• Blood dyscrasias (e.g. neutropaenia)

Rare (<0.1% frequency)

• Megaloblastic anaemia
• Methaemoglobinaemia
• Erythema multiforme
• Low blood sugar
• Hepatitis (liver swelling)
• Crystalluria (crystals in the urine)
• Urinary obstruction causing difficulty passing urine
• Lowered mental acuity
• Depression
• Tremor
• Aplastic anaemia
• Haemolytic anaemia
• Hyponatraemia
• Purpura
• Eosinophilia
• Agranulocytosis
• Serum sickness
• Anaphylaxis
• Allergic myocarditis
• Angioedema
• Drug fever
• Peri-arteritis nodosa
• Hepatic necrosis
• Pancreatitis
• Myelosuppression
• Haemolysis^{[lower-alpha 1]}
• Stevens-Johnson syndrome^{[lower-alpha 2]}
• Toxic epidermal necrolysis^{[lower-alpha 3]}
• Ataxia^{[lower-alpha 4]}
• Clostridium difficile colitis
• Aseptic meningitis^{[lower-alpha 5]}
• Pseudomembranous colitis
• Interstitial nephritis
• Fulminant hepatic necrosis
• Hypersensitivity of the respiratory tract
• Sore throat
• Pallor
• Arthralgia

Unknown frequency

• Hallucinations
• Cough
• Glossitis
• Stomatitis
• Fatigue
• Insomnia
• Impaired kidney function
• Pulmonary infiltration^{[lower-alpha 6]}
• Shortness of breath

Notes

1. Breakdown of red blood cells. This side effect most often occurs in people with glucose-6-phosphate dehydrogenase deficiency
2. A potentially fatal skin reaction that causes the skin to slough off
3. Basically a worse form of Stevens-Johnson syndrome
4. Incoordination; most often after IV use in HIV patients
5. Swelling of the membranes surrounding the brain and spinal cord without any obvious infectious cause
6. Sign of hypersensitivity

References

1. "Bactrim, Bactrim DS (trimethoprim/sulfamethoxazole) dosing, indications, interactions, adverse effects, and more". Medscape Reference. WebMD. Retrieved 13 January 2014.
2. "BACTRIM®" (PDF). TGA eBusiness Services. Roche Products Pty Limited. 18 September 2012. Retrieved 13 January 2014.
3. "BACTRIM DS (sulfamethoxazole and trimethoprim) tablet BACTRIM (sulfamethoxazole and trimethoprim) tablet [AR Scientific, Inc.]". DailyMed. AR Scientific, Inc. June 2013. Retrieved 13 January 2014.
4. "Co-Trimoxazole Tablets 80/400mg - Summary of Product Characteristics (SPC)". electronic Medicines Compendium. Actavis UK Ltd. 17 October 2012. Retrieved 13 January 2014.
5. Joint Formulary Committee (2013). British National Formulary (BNF) (65 ed.). London, UK: Pharmaceutical Press. ISBN 978-0-85711-084-8.
6. Rossi, S, ed. (2013). Australian Medicines Handbook (2013 ed.). Adelaide: The Australian Medicines Handbook Unit Trust. ISBN 978-0-9805790-9-3.
7. "e-Therapeutics+e-CPS". Sulfamethoxazole-Trimethoprim CPhA Monograph. Retrieved 28 March 2015.