Sulfamethoxazole & Trimethoprim

Sulfamethoxazole/trimethoprim treats several types of bacterial infections. This medication can cause you to sunburn more easily. Drink plenty of fluids with this medication.

Sulfamethoxazole & Trimethoprim Overview

Reviewed: May 21, 2013
Updated: 

Sulfamethoxazole/trimethoprim is a prescription medication used to treat bacterial infections of the urinary tract, lungs, intestines, and ears. It also treats infections that cause traveler’s diarrhea. This medication is a single formulation containing 2 drugs, sulfamethoxazole and trimethoprim. Sulfamethoxazole/trimethoprim both belong to a group of drugs called antibiotics. These work by stopping bacterial growth.

Sulfamethoxazole/trimethoprim comes in tablet and oral (by mouth) suspension forms and is taken up to 4 times a day, with or without food.

Common side effects of sulfamethoxazole/trimethoprim include diarrhea, vomiting, anorexia, and skin reactions like hives or itching.

Sulfamethoxazole & Trimethoprim Genetic Information

G6PD is an enzyme in your body that is responsible for helping red blood cells to work properly. Some patients are born with less of this enzyme in their bodies, leading to the destruction of red blood cells. When sulfamethoxazole/trimethoprim is used in patients with G6PD deficiency, they have a higher chance of experiencing hemolytic anemia (a condition in which the body does not have enough red blood cells to deliver oxygen to your tissues).

G6PD testing may be done to determine whether you are at a higher risk of experiencing hemolytic anemia if you are to be treated with sulfamethoxazole/trimethoprim.

Your doctor will select an alternative medication as sulfamethoxazole/trimethoprim should not be given to patients with G6PD deficiency.

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Sulfamethoxazole & Trimethoprim Cautionary Labels

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Uses of Sulfamethoxazole & Trimethoprim

Sulfamethoxazole/trimethoprim is a prescription medication used to treat bacterial infections of the urinary tract, lungs, intestines, ears, and infections that cause traveler’s diarrhea.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Sulfamethoxazole & Trimethoprim Brand Names

Sulfamethoxazole & Trimethoprim may be found in some form under the following brand names:

Sulfamethoxazole & Trimethoprim Drug Class

Sulfamethoxazole & Trimethoprim is part of the drug class:

Side Effects of Sulfamethoxazole & Trimethoprim

Serious side effects have been reported with sulfamethoxazole/trimethoprim. See “Drug Precautions” section.

Common side effects of sulfamethoxazole/trimethoprim include diarrhea, vomiting, anorexia, and skin reactions like hives or itching.

This is not a complete list of sulfamethoxazole/trimethoprim side effects. Ask your doctor or pharmacist for more information.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Sulfamethoxazole & Trimethoprim Interactions

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

  • warfarin (Coumadin, Jantoven)
  • phenytoin (Dilantin)
  • methotrexate (Trexall, Rheumatrex)
  • cyclosporine (Gengraf, Neoral, Sandimmune)
  • digoxin (Lanoxin)
  • pyrimethamine (Daraprim)
  • indomethacin (Indocin)
  • leucovorin (Wellcovorin)
  • thiazide diuretics such as hydrochlorothiazide (Esidrix, HydroDiuril, Hydro-Par, Oretic) and chlororthalidone (Thalitone, Hygroton)
  • medications that use the enzyme CYP2C8 such as pioglitazone (Actos), repaglinide (Prandin), and rosiglitazone (Avandia)
  • medications that use the enzyme CYP2C9 such as glipizide (Glucotrol) and glyburide (Micronase, DiaBeta)
  • metformin (Glucophage)

This is not a complete list of sulfamethoxazole/trimethoprim drug interactions. Ask your doctor or pharmacist for more information.

Sulfamethoxazole & Trimethoprim Precautions

Serious side effects have been reported with sulfamethoxazole/trimethoprim including the following:

  • hypersensitivity (severe allergic reaction). Signs of a hypersensitivity reaction, which include the following:
    • chest pain
    • swelling of the face, eyes, lips, tongue, arms, or legs
    • difficulty breathing or swallowing
    • fainting
    • rash
  • increased risk of bleeding. This may be due to thrombocytopenia, or when your platelet count level drops. Tell your healthcare provider right away if you have some or all of the following symptoms of bleeding:
    • red or purple spots seen on skin
    • bleeding that does not resolve within a few minutes
    • abnormal or easy bruising
  • diarrhea. Diarrhea is a common problem caused by antibiotics, and it usually ends when the antibacterial is discontinued. Sometimes after starting treatment with antibiotics, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as 2 or more months after having taken their last dose of the antibacterial. If diarrhea is severe or lasts more than 2 or 3 days, contact your doctor, as this may be a sign of an infection of the bowels.
  • hyperkalemia (high potassium levels in body). Hyperkalemia can cause an arrhythmia, or a rapid heart rate or rhythm. Tell your healthcare provider right away if you have some or all of the following symptoms of hyperkalemia:
    • shortness of breath
    • fast or slow heartbeat
    • lightheadedness or dizziness
    • chest pain
    • sweating
    • skipping heartbeats
  • kidney stones. To prevent kidney stones, it is recommended to drink plenty of fluids. Tell your healthcare provider right away if have some or all of the following symptoms of kidney stones:
    • extreme pain in your back or side that will not go away
    • blood in your urine
    • fever and chills
    • vomiting
    • urine that smells bad or looks cloudy
    • a burning feeling when you urinate

Do not take sulfamethoxazole/trimethoprim if you:

  • have a known allergic reaction to trimethoprim or sulfamethoxazole or to any of this medication's ingredients
  • are less than 2 months of age
  • have a specific type of bacterial infection (group A beta-hemolytic streptococcal bacteria)
  • have a history of drug-induced immune thrombocytopenia (low platelet count) with use of trimethoprim and/or sulfa-containing drugs
  • have a history of anemia (low red blood cell count) due to a folate deficiency
  • have severe liver or kidney damage
  • are pregnant or are breastfeeding

Sulfamethoxazole & Trimethoprim Food Interactions

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of sulfamethoxazole/trimethoprim, there are no specific foods that you must exclude from your diet when receiving sulfamethoxazole/trimethoprim.

 

Inform MD

Before taking sulfamethoxazole/trimethoprim, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

  • have a known hypersensitivity to trimethoprim and/or sulfa-containing drugs
  • have a history of drug-induced immune thrombocytopenia (low platelet counts) with use of trimethoprim and/or sulfa-containing drugs
  • are being treated for HIV/AIDs
  • have a history of anemia (low red blood cell count) due to folate deficiency
  • have a condition called porphyria, which is when a compound in your body (heme) and its ability to carry oxygen around in your blood is impaired
  • have a history of thyroid dysfunction
  • have a decreased ability to ingest food, to absorb nutrients, or are malnourished
  • have asthma
  • have a deficiency of glucose-6-phosphate
  • have liver damage
  • have kidney dysfunction
  • are pregnant or are breastfeeding

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Sulfamethoxazole & Trimethoprim and Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Sulfamethoxazole/trimethoprim falls into category D. It is strongly not recommended (“contraindicated") for use in pregnant patients because sulfonamides cross the placental barrier, which may cause brain damage to the unborn child. In addition, sulfamethoxazole and trimethoprim may interfere with folic acid activity in the body. This may further negatively affect the unborn child.

In summary, sulfamethoxazole/trimethoprim should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Sulfamethoxazole & Trimethoprim and Lactation

Tell your doctor if you are breastfeeding or plan to breastfeed.

You should not take sulfamethoxazole/trimethoprim if you are breastfeeding. Sulfamethoxazole is able to pass into breast milk, which may cause brain damage to your baby.

Sulfamethoxazole & Trimethoprim Usage

Take sulfamethoxazole/trimethoprim exactly as prescribed.

Sulfamethoxazole/trimethoprim comes in tablet and oral (by mouth) suspension forms and is taken up to 4 times a day, with or without food.

Shake oral (by mouth) suspension well before using.

If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of sulfamethoxazole/trimethoprim at the same time.

Sulfamethoxazole & Trimethoprim Dosage

Take sulfamethoxazole/trimethoprim exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The sulfamethoxazole/trimethoprim dose your doctor recommends will be based on:

  • the condition being treated
  • other medical conditions you have
  • other medications you are taking
  • how you respond to this medication
  • your kidney function
  • your body size (body surface area)
  • your age
  • your weight

The recommended dose range for sulfamethoxazole/trimethoprim in adults is 160 mg/80 mg to 2000 mg/400 mg.

The recommended dose range for sulfamethoxazole/trimethoprim in children is 80 mg/40 mg to 2000 mg/400 mg.

Sulfamethoxazole & Trimethoprim Overdose

If you take too much sulfamethoxazole/trimethoprim, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

 

Other Requirements

  • Store at controlled room temperature 15°-30°C (59°-86°F).
  • Protect from light.
  • Dispense in a tight, light-resistant container as defined in the USP.
  • Keep this and all medicines out of the reach of children.