Sulfamethoxazole/trimethoprim (By mouth)
Sulfamethoxazole (sul-fa-meth-OX-a-zole), Trimethoprim (trye-METH-oh-prim)
Treats or prevents infections. This medicine contains a sulfa drug (sulfonamide).
Sulfatrim Pediatric, Septra, SMZ-TMP Pediatric, Sulfatrim, Bactrim DS, Bactrim
There may be other brand names for this medicine.
When This Medicine Should Not Be Used
Do not use this medicine if you have had an allergic reaction to trimethoprim, sulfamethoxazole, or any sulfa drug. Do not use this medicine if you are pregnant or breastfeeding, or in some situations if you have severe liver or kidney problems. Do not use this medicine if you have anemia caused by low levels of folic acid in your body. Do not use this medicine if you have a history of drug-induced thrombocytopenia. This medicine should not be given to infants younger than 2 months.
How to Use This Medicine
- Your doctor will tell you how much of this medicine to use and how often. Do not use more medicine or use it more often than your doctor tells you to.
- Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup.
- Drink extra fluids so you will pass more urine while you are using this medicine. This will keep your kidneys working well and help prevent kidney problems.
- Keep using this medicine for the full treatment time, even if you feel better after the first few doses. Your infection may not clear up if you stop using the medicine too soon.
If a dose is missed:
- If you miss a dose or forget to use your medicine, use it as soon as you can. If it is almost time for your next dose, wait until then to use the medicine and skip the missed dose. Do not use extra medicine to make up for a missed dose.
How to Store and Dispose of This Medicine
- Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Do not freeze the oral liquid.
- Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
- Keep all medicine away from children and never share your medicine with anyone.
Drugs and Foods to Avoid
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.
- Make sure your doctor knows if you also use leucovorin, digoxin (Lanoxin®), indomethacin (Indocin®), a diuretic (water pill, such as hydrochlorothiazide, spironolactone, triamterene, Aldactone®), certain blood pressure medicine (such as benazepril, enalapril, lisinopril, Lotrel®, Vasotec®, Zestoretic®, Zestril®), or a blood thinner (such as warfarin, Coumadin®, Jantoven®).
- Make sure your doctor knows if you also use amantadine (Symmetrel®), cyclosporine (Gengraf®, Neoral®, Sandimmune®), methotrexate (Rheumatrex®, Trexall®), phenytoin (Dilantin®), medicines to treat depression (such as amitriptyline, nortriptyline, Elavil®), diabetes medicine that you take by mouth (such as glimepiride, glyburide, metformin, Actos®, Janumet®, Januvia®), or medicine to prevent malaria (such as pyrimethamine, Daraprim®).
Warnings While Using This Medicine
- Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using the medicine, tell your doctor right away.
- Make sure your doctor knows if you have kidney disease, liver disease, diabetes, malabsorption syndrome (difficulty absorbing nutrients from food), malnutrition, folate deficiency, high potassium in the blood, porphyria, thyroid problems, a history of alcoholism, or if you take medicines to prevent seizures. Tell your doctor if you have asthma or severe allergies, especially if you are allergic to any medicines. It is important for your doctor to know if you have HIV or AIDS, because this medicine might work differently. Tell your doctor if you have a rare condition called glucose-6-phosphate dehydrogenase (G6PD) deficiency.
- Very rarely, this medicine has caused severe side effects. If you start to have a skin rash, or if you think you are having a severe reaction, stop taking this medicine and call your doctor right away. Symptoms of a severe reaction include a sore throat, fever, muscle pain, cough, and trouble breathing. Other symptoms are a skin rash, purple spots on your skin, or very pale or yellow skin.
- This medicine may lower the number of platelets in your body, which are necessary for proper blood clotting. This may cause you to bleed or get infections more easily. Talk with your doctor if you have concerns about this.
- If you have severe diarrhea, ask your doctor before taking any medicine to stop the diarrhea. Check with your doctor right away if the diarrhea continues. Diarrhea may occur 2 months or more after you stop taking this medicine.
- Your doctor will need to check your blood or urine at regular visits while you are using this medicine. Be sure to keep all appointments.
- Make sure any doctor or dentist who treats you knows that you are using this medicine. This medicine may affect the results of certain medical tests.
Possible Side Effects While Using This Medicine
Call your doctor right away if you notice any of these side effects:
- Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
- Blistering, peeling, or red skin rash
- Change in how much or how often you urinate
- Chest pain, cough, or shortness of breath
- Confusion, weakness, uneven heartbeat, or numbness or tingling in your hands, feet, or lips
- Dark urine or pale stools, pain in your upper stomach, yellow skin or eyes
- Diarrhea that may contain blood
- Severe stomach pain, cramps, or bloating
- Unusual bleeding, bruising, or weakness
If you notice these less serious side effects, talk with your doctor:
- Nausea, vomiting, loss of appetite
If you notice other side effects that you think are caused by this medicine, tell your doctor
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088
- Last Reviewed on 06/12/2013
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This page was last updated: September 18, 2013