By Medically reviewed by hellodoktor

Generic Name: Cotrimoxazole Brand Name(s): Generics only. No brands available.


What is cotrimoxazole used for?

Cotrimoxazole is commonly used for certain bacterial infections treatment, such as pneumonia (a lung infection), bronchitis (infection of the tubes leading to the lungs), and infections of the urinary tract, ears, and intestines. It is also used to treat ‘travelers’ diarrhea.

Co-trimoxazole is a combination of trimethoprim and sulfamethoxazole, also it is in the class of medications called sulfonamides. It works by stopping the growth of bacteria. Antibiotics will not kill viruses that can cause colds, flu or other viral infections.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

How should I take cotrimoxazole?

  • Co-trimoxazole comes as a tablet and a suspension (liquid) to take by mouth. It usually is taken two times a day but may be taken up to four times a day when used to treat certain severe lung infections. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take co-trimoxazole exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
  • You should begin to feel better during the first few days of treatment with co-trimoxazole. If your symptoms do not improve or if they get worse, call your doctor.
  • Shake the liquid well before each use to mix the medication evenly.
  • Take co-trimoxazole until you finish the prescription, even if you feel better. Do not stop taking co-trimoxazole without talking to your doctor. If you stop taking co-trimoxazole too soon or skip doses, your infection may not be completely treated and the bacteria may become resistant to antibiotics.

How do I store cotrimoxazole?

Cotrimoxazole is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store cotrimoxazole in the bathroom or the freezer. There may be different brands of cotrimoxazole that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush cotrimoxazole down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using cotrimoxazole?

  • Tell your doctor and pharmacist if you are allergic to co-trimoxazole, any other medications, or any ingredients in co-trimoxazole tablets and suspension. Ask your pharmacist for a list of ingredients.
  • Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • Tell your doctor if you have or have ever had thrombocytopenia (less than normal number of platelets) caused by taking sulfonamides or trimethoprim; megaloblastic anemia (abnormal red blood cells) caused by folate deficiency (low blood levels of folic acid), phenylketonuria (PKU, an inherited condition in which a special diet must be followed to prevent mental retardation), or liver or kidney disease. Your doctor may tell you not to take co-trimoxazole. Co-trimoxazole should not be used in children less than 2 months of age.
  • Tell your doctor if you have or have ever had severe allergies; asthma; low levels of folic acid in the body which may be caused by malnutrition (you do not eat or cannot digest the nutrients needed for good health); human immunodeficiency virus (HIV) infection; porphyria (an inherited blood disease that may cause skin or nervous system problems); thyroid disease; or glucose-6-phosphate dehydrogenase (G-6-PD) deficiency (an inherited blood disease).
  • Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while taking co-trimoxazole, call your doctor immediately because it can harm the fetus.
  • Plan to avoid unnecessary or prolonged exposure to sunlight and wear protective clothing, sunglasses, and sunscreen. Co-trimoxazole may make your skin sensitive to sunlight.

Is it safe during pregnancy or breastfeeding?

There are no adequate studies in women for determining risk when using cotrimoxazole during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking cotrimoxazole. Cotrimoxazole is pregnancy risk category C, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk;
  • B=No risk in some studies;
  • C=There may be some risk;
  • D=Positive evidence of risk;
  • X=Contraindicated;
  • N=Unknown.

Side effects

What side effects can occur from cotrimoxazole?

  • Nausea;
  • Vomiting;
  • Loss of appetite;
  • Allergic reactions;
  • High levels of potassium in the blood.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side effect, please consult your doctor or pharmacist.


What drugs may interact with cotrimoxazole?

Cotrimoxazole may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. A total of 421 drugs (1578 brand and generic names) are known to interact with cotrimoxazole, there are some medications:

  • Acyclovir;
  • Amlodipine;
  • Atenolo;
  • Lisinopril;
  • Ciprofloxacin;
  • Fluconazole;
  • Metronidazole;
  • Valganciclovir;

 To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with cotrimoxazole?

Cotrimoxazole may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with cotrimoxazole?

Cotrimoxazole may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using cotrimoxazole.

What is the dose of cotrimoxazole for an adult?

Usual adult dose for Pneumocystis Pneumonia

  • 15 to 20 mg/kg/day (trimethoprim component) orally or IV in 3 to 4 equally divided doses every 6 to 8 hours; according to 1 investigator, 10 to 15 mg/kg/day (trimethoprim component) IV was sufficient in 10 patients.
  • Duration: 14 to 21 days. Treatment should be followed by chronic suppressive therapy.
  • If the patient is hypoxemic, IV therapy is recommended. Oral therapy may be substituted once the patient is able to tolerate oral medications and improves clinically. During oral therapy, desirable sulfamethoxazole levels are 100 to 150 mcg/ml. Levels exceeding 200 mcg/ml are associated with more side effects. Trimethoprim levels should be maintained between 5 to 8 mcg/ml.

Usual adult dose for Traveler’s Diarrhea

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours for 5 days.

Usual adult dose for Bronchitis

Acute bacterial exacerbation of chronic bronchitis: Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours for 14 days.

Usual adult dose for Urinary Tract Infection

  • Oral: Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours for 10 to 14 days.
  • IV: Severe infection: 8 to 10 mg/kg/day (trimethoprim component) IV in 2 to 4 equally divided doses every 6, 8, or 12 hours for up to 14 days; maximum recommended dose is 960 mg (trimethoprim component) per day.

What is the dose of cotrimoxazole for a child?

  • 6 to 12 years old: two 5 ml spoonfuls in a morning and two 5 ml spoonfuls in an evening.
  • 6 months to 5 years: one 5 ml spoonful in a morning and one 5 ml spoonful in an evening.
  • 6 weeks to 5 months: one 2.5 ml spoonful in a morning and one 2.5 ml spoonful in an evening.
  • Co-Trimoxazole should be taken for at least five days.
  • Make sure that your child finishes the course of Co-Trimoxazole which their doctor has prescribed.

How is cotrimoxazole available?

Cotrimoxazole is available in the following dosage forms and strengths: Co-Trimoxazole 40 mg/200 mg per 5 ml Paediatric Suspension.

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services (115) or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of cotrimoxazole, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: October 26, 2016 | Last Modified: September 13, 2019

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