Generic Name: sulfamethoxazole and trimethoprim (oral) (SUL fa meth OX a zole and trye METH oh prim)
Brand Name: Bactrim, Bactrim DS
Medically reviewed by Philip Thornton, DipPharm. Last updated on March 3, 2021.
What is Bactrim?
Bactrim contains a combination of sulfamethoxazole and trimethoprim. Sulfamethoxazole and trimethoprim are are both antibiotics that treat different types of infection caused by bacteria.
Bactrim may also be used for purposes not listed in this medication guide.
You should not use Bactrim if you have severe liver disease, kidney disease that is not being monitored, anemia caused by folic acid deficiency, if you take dofetilide, or if you have had low platelets caused by using trimethoprim or a sulfa drug.
You should not take sulfamethoxazole and trimethoprim if you are pregnant or breastfeeding.
Before taking this medicine
You should not use Bactrim if you are allergic to sulfamethoxazole or trimethoprim, or if you have:
severe liver disease;
kidney disease that is not being treated or monitored;
anemia (low red blood cells) caused by folic acid deficiency;
a history of low blood platelets after taking trimethoprim or any sulfa drug; or
if you take dofetilide (Tikosyn).
Do not use Bactrim if you are pregnant. This medicine could harm the unborn baby or cause birth defects. Use effective birth control, and tell your doctor if you are pregnant or become pregnant.
Do not breastfeed while using this medicine.
This medicine should not be given to a child younger than 2 months old.
To make sure Bactrim is safe for you, tell your doctor if you have:
kidney or liver disease;
a folate (folic acid) deficiency;
a thyroid disorder;
high levels of potassium in your blood;
porphyria, or glucose-6-phosphate dehydrogenase (G6PD) deficiency; or
if you use a blood thinner (such as warfarin) and you have routine "INR" or prothrombin time tests.
How should I take Bactrim?
Take Bactrim exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets.
Drink plenty of fluids to prevent kidney stones while you are using this medicine.
Sulfamethoxazole and trimethoprim doses are based on weight in children. Use only the recommended dose when giving this medicine to a child.
Use this medicine for the full prescribed length of time, even if your symptoms quickly improve. Skipping doses can increase your risk of infection that is resistant to medication. This medicine will not treat a viral infection such as the flu or a common cold.
You may need frequent medical tests.
This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using Bactrim.
Store at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Use the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not use two doses at one time.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include loss of appetite, vomiting, fever, blood in your urine, yellowing of your skin or eyes, confusion, or loss of consciousness.
What should I avoid while using Bactrim?
Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, call your doctor before using anti-diarrhea medicine.
Bactrim could make you sunburn more easily. Avoid sunlight or tanning beds. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.
Bactrim side effects
Get emergency medical help if you have signs of an allergic reaction to Bactrim (hives, cough, chest pain, shortness of breath, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).
Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, joint pain, muscle aches, severe weakness, pale skin, unusual bruising, or yellowing of your skin or eyes.
Call your doctor at once if you have:
severe stomach pain, diarrhea that is watery or bloody (even if it occurs months after your last dose);
a skin rash, no matter how mild;
yellowing of your skin or eyes;
new or unusual joint pain;
increased or decreased urination;
swelling, bruising, or irritation around the IV needle;
increased thirst, dry mouth, fruity breath odor;
new or worsening cough, fever, trouble breathing;
high potassium level - nausea, weakness, tingly feeling, chest pain, irregular heartbeats, loss of movement;
low sodium level - headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady; or
low blood cell counts - fever, chills, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath.
Common Bactrim side effects may include:
nausea, vomiting, loss of appetite; or
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect Bactrim?
Tell your doctor about all your current medicines. Many drugs can affect sulfamethoxazole and trimethoprim, especially:
This list is not complete and many other drugs may interact with sulfamethoxazole and trimethoprim. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.
Frequently asked questions
- Can you take Bactrim DS if you're allergic to penicillin?
- How long does it take for a boil to heal while taking Bactrim?
- Can I drink alcohol while taking sulfamethoxazole / trimethoprim DS tablets?
- What dose of co-trimoxazole is used in a patient with a UTI?
More about Bactrim (sulfamethoxazole / trimethoprim)
- Side Effects
- During Pregnancy
- Dosage Information
- Patient Tips
- Drug Images
- Drug Interactions
- Compare Alternatives
- Support Group
- Pricing & Coupons
- En Español
- 504 Reviews
- Generic Availability
- Drug class: sulfonamides
Related treatment guides
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Bactrim only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Copyright 1996-2021 Cerner Multum, Inc. Version: 11.01.