This page contains brief details about the drug , it's indication, dosage & administaration, mechanism of action, related brands with strength, warnings and common side effects.

Background and Date of Approval

Cotrimoxazole was initially approved by the United States Food and Drug Administration (FDA) on October 15, 1973.

Mechanism of Action of undefined

Cotrimoxazole involves a synergistic inhibition of bacterial folate synthesis. It combines trimethoprim, which blocks a specific enzyme in the pathway, with sulfamethoxazole, which competes with para-aminobenzoic acid, a folate precursor. This dual action disrupts the bacteria's ability to synthesize DNA, RNA, and proteins, inhibiting their growth and effectively treating infections.

Uses of undefined

Cotrimoxazole is utilized to treat a range of bacterial infections. Its primary applications encompass urinary tract infections (UTIs), respiratory tract infections, gastrointestinal infections, skin and soft tissue infections, traveler's diarrhea, and the prevention of Pneumocystis jirovecii pneumonia (PCP) in immunocompromised individuals. Additionally, it may address conditions like toxoplasmosis and nocardiosis. 

undefined Drug administaration and Dosage available

Cotrimoxazole can be administered through two main routes, which are oral and intravenous. The oral route involves taking tablets or liquid by mouth, while the intravenous route delivers the medication directly into the bloodstream. The administration route choice depends on the infection's severity and the patient's condition.

Warnings, Precautions and Side Effects of undefined


Cotrimoxazole contains sulfamethoxazole, which can trigger severe allergic reactions, including skin rash, fever, and potentially life-threatening conditions like Stevens-Johnson syndrome. It might lead to blood disorders such as anemia, thrombocytopenia, and agranulocytosis.  Serious liver and kidney problems, including jaundice, dark urine, and changes in urination patterns, are possible. It can interfere with folate metabolism, potentially leading to folate deficiency. Breathing difficulties and lung inflammation might occur, especially in individuals with pre-existing respiratory conditions.


Discontinue use and seek medical help if allergic reactions occur after using Cotrimoxazole. Monitor kidney and liver function regularly, especially if you have pre-existing conditions. Watch for severe allergic reactions, blood disorders, and skin reactions. Seek medical attention for any severe symptoms. Stay hydrated to prevent potential kidney problems, especially in hot weather or during gastrointestinal disturbances.

Side Effects

Cotrimoxazole use may lead to a range of side effects. Commonly observed effects encompass nausea, vomiting, diarrhea, and mild skin rash. In contrast, more severe reactions involve severe allergic responses, blood disorders affecting red and white blood cells or platelets, liver or kidney issues, and rare but critical skin reactions like Stevens-Johnson syndrome. Gastrointestinal distress, respiratory problems, hyperkalemia, and potential impacts on the central nervous system are also possible.

Word Of Advice

Inform your healthcare provider about allergies, medical history (including kidney and liver problems), and medications you are taking before using Cotrimoxazole. Discuss potential risks if pregnant, breastfeeding, or planning pregnancy. Monitor kidney and liver function regularly. Watch for severe allergic reactions, blood disorders, and serious skin reactions. Stay hydrated and be cautious in sunlight. Follow prescribed dosages and avoid changing medications without consulting a healthcare provider. While traveling, plan for medication supply. Store properly, dispose of unused medication, and immediately address emergencies. Maintain communication with your healthcare provider and report any new symptoms. 

Frequently Asked Question


  1. KD Tripathi, Essentials of Medical Pharmacology, Sulfonamides, Cotrimoxazole, and Quinolones, 7th edition, 2013, 706-708.
  2. Goodman & Gilman’s, The Pharmacological Basis of Therapeutics, Sulfonamides, Trimethoprim-Sulfamethoxazole, Quinolones, and Agents for urinary tract infections, 12th edition, 2011, 1468-1470.
  3. Aspen, Electronic medicines compendium (EMC), [ Revised on 12th Jun 2023] [ Accessed on 31st August 2023],
  4. Sun Pharmaceutical Industries, Inc, US Food and Drug Administration, [ Revised on 3/2017] [ Accessed on 31st August 2023,


The drug information on this page is not a substitute for medical advice; it is meant for educational purposes only. For further details, consult your doctor about your medical condition to know if you can receive this treatment.