Bactrim or Co-Trimoxazole

Other Names: Bactrim, Bactrim DS (double strength), Bethaprim, Comoxol, Cotrim, Septra, Septra DS (double strength), Sulfatrim

Why is this drug prescribed?
Co-trimoxazole is a combination of trimethoprim and sulfamethoxazole, a "sulfa" drug. It eliminates bacteria that cause various infections, especially infections of the urinary tract, lungs (pneumonia), ears and intestines.

When should it be used?
Co-trimoxazole usually is taken two times a day. Follow the instructions on your prescription label carefully, and ask your pharmacist to explain any part that you do not understand. Doses should be taken at evenly spaced intervals around the clock. For example, if you are to take this drug twice a day, take a dose every 12 hours.

How should it be used?
This drug comes in tablets, suspension (oral liquid), and injection form. Your prescription label tells you how much to take at each dose. You may obtain a specially marked measuring spoon from your pharmacist to be sure of an accurate dose of the suspension. Shake the suspension well before each use to mix the medication evenly. Ask your pharmacist any questions you have about refilling your prescription.

What special instructions should I follow while using this drug?
Drink at least eight glasses of liquid (water, tea, coffee, soft drinks, milk, or fruit juice) every day. Take all the medication prescribed, even after you begin to feel well. Failure to do so could allow the infection to return. Do not stop taking this medication without our consent. If your symptoms do not improve within a few days or if you still have signs of infection after taking all your medication, contact us. Keep all appointments with us and the laboratory. You probably will have periodic blood tests if you take this medication for more than two weeks, and a follow up urine test if you take it for a urinary tract infection.

What should I do if I forget to take a dose?
Take the missed dose as soon as you remember and resume your regular dosing schedule. If you remember the missed dose near the time you are due to take the next dose, space the missed dose and the regularly scheduled dose two to three hours apart. Then resume your regular dosing schedule.

What side effects can this drug cause? What can I do about them?

  • Nausea, vomiting, abdominal pain, diarrhea
    Take the drug with food. If these effects are severe or persist, contact us.
  • Skin rash, itching, sore throat, fever, chills, mouth sores, unusual bruising or bleeding, yellowing of skin or eyes, paleness, joint aches
    Contact us.

What other precautions should I follow while using this drug?
Before you take this drug, tell us what prescription and nonprescription drugs you are taking, particularly Methotrexate, Phenytoin and Warfarin. Before you take co-trimoxazole, tell us if you ever had a bad reaction to any sulfa drug, "water pills" or oral diabetes drug; if you have liver or kidney disease, asthma, severe allergies, or G-6-PD deficiency (an inherited blood disease); or if you are pregnant (or may become pregnant) or breast-feeding. This medication can make your skin more sensitive to sunlight (and sunlamps). If you will be outside for long periods, wear protective clothing and use a sunscreen preparation.