Sulfamethoxazole and Trimethoprim

Adult Medication

Brand Names: US

Bactrim; Bactrim DS; Sulfatrim Pediatric

Brand Names: Canada

Apo-Sulfatrim; Apo-Sulfatrim DS; Apo-Sulfatrim Pediatric; Protrin DF; Septra Injection; Teva-Trimel; Teva-Trimel DS; Trisulfa; Trisulfa DS; Trisulfa S

What is this drug used for?

  • It is used to treat or prevent bacterial infections.

What do I need to tell my doctor BEFORE I take this drug?

  • If you have an allergy to sulfamethoxazole, trimethoprim, or any other part of this drug.
  • If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
  • If you have anemia caused by a lack of folic acid.
  • If you have any of these health problems: Kidney disease or liver disease.
  • If you have ever had a low platelet count when using trimethoprim or a sulfa (sulfonamide) drug.
This is not a list of all drugs or health problems that interact with this drug.
Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take this drug?

All products:

  • Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • This drug may affect certain lab tests. Tell all of your health care providers and lab workers that you take this drug.
  • Do not use longer than you have been told. A second infection may happen.
  • Be careful if you have G6PD deficiency. Anemia may happen.
  • If you have high blood sugar (diabetes), you will need to watch your blood sugar closely.
  • Talk with your doctor before you drink alcohol.
  • You may get sunburned more easily. Avoid sun, sunlamps, and tanning beds. Use sunscreen and wear clothing and eyewear that protects you from the sun.
  • If you are 65 or older, use this drug with care. You could have more side effects.
  • Do not give this drug to an infant younger than 2 months of age.
  • This drug may cause harm to the unborn baby if you take it while you are pregnant.
  • Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using this drug while you are pregnant.
  • Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.


  • Some products have benzyl alcohol. Do not give a product that has benzyl alcohol in it to a newborn. Talk with the doctor to see if this product has benzyl alcohol in it.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

All products:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of a high potassium level like a heartbeat that does not feel normal; change in thinking clearly and with logic; feeling weak, lightheaded, or dizzy; feel like passing out; numbness or tingling; or shortness of breath.
  • Not able to pass urine or change in how much urine is passed.
  • Muscle or joint pain.
  • Purple patches on the skin or mouth.
  • Shortness of breath.
  • It is common to have diarrhea when taking this drug. Rarely, a very bad form of diarrhea called Clostridium difficile (C diff)–associated diarrhea (CDAD) may occur. Sometimes, this has led to a deadly bowel problem (colitis). CDAD may happen while you are taking this drug or within a few months after you stop taking it. Call your doctor right away if you have stomach pain or cramps, very loose or watery stools, or bloody stools. Do not try to treat loose stools without first checking with your doctor.
  • Very bad and rarely deadly effects have happened with sulfa (sulfonamide) drugs like this one. These effects have included liver problems, blood problems, and very bad skin reactions (Stevens-Johnson syndrome/toxic epidermal necrolysis). Call your doctor right away if you have a rash; red, swollen, blistered, or peeling skin; red or irritated eyes; sores in your mouth, throat, nose, or eyes; fever, chills, or sore throat; cough that is new or worse; feeling very tired or weak; any bruising or bleeding; or signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.


  • Irritation where the shot is given.
  • Pain where the shot was given.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
  • Upset stomach or throwing up.
  • Loose stools (diarrhea).
  • Not hungry.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to your national health agency.

How is this drug best taken?

Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.

All products:

  • To gain the most benefit, do not miss doses.
  • Keep taking this drug as you have been told by your doctor or other health care provider, even if you feel well.
  • Take this drug at the same time of day.
  • Drink lots of noncaffeine liquids unless told to drink less liquid by your doctor.

All oral products:

  • Take with or without food. Take with food if it causes an upset stomach.
  • Take with a full glass of water.

Liquid (suspension):

  • Shake well before use.
  • Measure liquid doses carefully. Use the measuring device that comes with this drug. If there is none, ask the pharmacist for a device to measure this drug.


  • It is given as a shot into a vein over a period of time.
  • If you will be giving yourself the shot, your doctor or nurse will teach you how to give the shot.
  • Follow how to use carefully.
  • Do not use if the solution is cloudy, leaking, or has particles.
  • Do not use if solution changes color.
  • Throw away needles in a needle/sharp disposal box. Do not reuse needles or other items. When the box is full, follow all local rules for getting rid of it. Talk with a doctor or pharmacist if you have any questions.

What do I do if I miss a dose?

  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

How do I store and/or throw out this drug?

All oral products:

  • Store at room temperature.
  • Store in a dry place. Do not store in a bathroom.
  • Protect from light.


  • Most of the time, this drug will be given in a hospital or doctor’s office. If stored at home, follow how to store as you were told by the doctor.

All products:

  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Check with your pharmacist about how to throw out unused drugs.

General drug facts

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else’s drugs.
  • Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
  • Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
  • Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Consumer Information Use and Disclaimer

This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.

Last Reviewed Date



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