Sulfamethoxazole/trimethoprim (By injection)
Sulfamethoxazole (sul-fa-meth-OX-a-zole), Trimethoprim (trye-METH-oh-prim)
Treats severe infections caused by bacteria (germs). This medicine is a "sulfa drug" (sulfonamide).
There may be other brand names for this medicine.
When This Medicine Should Not Be Used:
You should 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 breast feeding. You should not use this medicine if you have anemia (a problem with your blood) caused by not having enough folic acid in your body. This medicine should not be given to infants under 2 months of age.
How to Use This Medicine:
- Your doctor will prescribe your dose and schedule. This medicine is given through a needle placed in a vein.
- A nurse or other health provider will give you this medicine.
- You may be taught how to give your medicine at home. Make sure you understand all instructions before giving yourself an injection. Do not use more medicine or use it more often than your doctor tells you to.
- Use a new needle and syringe each time you inject your medicine.
- Drink extra fluids so you will urinate more often and help prevent kidney problems.
- Take all of the medicine in your prescription to clear up your infection, even if you feel better after the first few doses.
If a dose is missed:
- You must use this medicine on a fixed schedule. Call your doctor or pharmacist if you miss a dose.
How to Store and Dispose of This Medicine:
- If you store this medicine at home, keep it at room temperature, away from heat and direct light.
- Throw away used needles in a hard, closed container that the needles cannot poke through. Keep this container away from children and pets.
- Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any leftover medicine, containers, and other supplies. Throw away old medicine after the expiration date has passed.
- Keep all medicine out of the reach of children. 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 are also using methotrexate (Rheumatrex®), diuretics or "water pills" (such as hydrochlorothiazide, Aldactazide®, Diuril®, Dyazide®, Enduron®, Maxzide®, Zaroxolyn®).
- Tell your doctor if you are also using medicine for seizures (such as Depakote®, Dilantin®, Keppra, Luminal®, Tegretol®).
Warnings While Using This Medicine:
- Make sure your doctor knows if you have HIV or AIDS, liver disease, kidney disease, asthma, epilepsy (seizures), or G6PD (glucose 6-phosphate dehydrogenase deficiency), or if you drink large amounts of alcohol.
- Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
- This medicine can cause diarrhea. Call your doctor if the diarrhea becomes severe, does not stop, or is bloody. Do not take any medicine to stop diarrhea until you have talked to your doctor. Diarrhea can occur 2 months or more after you stop taking this medicine.
- 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, or the color of your skin turning very pale or yellow, or having purple spots.
- Tell any doctor or dentist who treats you that you are using this medicine. This medicine may affect certain medical test results.
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, red skin rash.
- Dark-colored urine or pale stools.
- Fever, sore throat, pale skin, body aches.
- Loss of appetite, pain in your upper stomach.
- Nausea, vomiting, dizziness, confusion.
- Unusual bleeding, bruising, or weakness.
- Yellowing of your skin or the whites of your eyes.
If you notice these less serious side effects, talk with your doctor:
- Depression, nervousness.
- Irritation or swelling of your skin where the needle is placed.
- Trouble sleeping.
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 Updated: 6/2/2022
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