Sulfamethoxazole and trimethoprim

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.

Sulfamethoxazole / trimethoprim Side Effects

Medically reviewed by Drugs.com. Last updated on Oct 21, 2022.

Applies to sulfamethoxazole / trimethoprim: oral suspension, oral tablet. Other dosage forms:

Serious side effects

Along with its needed effects, sulfamethoxazole/trimethoprim may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking sulfamethoxazole / trimethoprim:

More common

• Black, tarry stools
• blistering, peeling, or loosening of the skin
• changes in skin color
• chest pain or tightness
• chills
• clay-colored stools
• cough or hoarseness
• dark urine
• diarrhea
• dizziness
• fever
• general feeling of tiredness or weakness
• headache
• itching, skin rash
• joint or muscle pain
• light-colored stools
• loss of appetite
• lower back or side pain
• nausea
• pain, tenderness, or swelling of the foot or leg
• painful or difficult urination
• pale skin
• red skin lesions, often with a purple center
• red, irritated eyes
• sore throat
• sores, ulcers, or white spots in the mouth or on the lips
• stomach pain
• swollen or painful glands
• trouble breathing
• unpleasant breath odor
• unusual bleeding or bruising
• vomiting of blood
• yellow eyes or skin

Incidence not known

• Back, leg, or stomach pains
• bleeding gums
• blindness or vision changes
• bloating
• blood in the urine or stools
• bluish-colored lips, fingernails, or palms
• burning, crawling, itching, numbness, painful, prickling, “pins and needles”, or tingling feelings
• burning of the face or mouth
• cloudy urine
• clumsiness or unsteadiness
• confusion
• constipation
• continuing ringing or buzzing or other unexplained noise in the ears
• cracks in the skin
• decreased frequency or amount of urine
• difficulty with swallowing
• fainting spells
• fast, pounding, or irregular heartbeat or pulse
• general body swelling
• general feeling of discomfort or illness
• hair loss
• hearing loss
• hives
• increased thirst
• indigestion
• large, flat, blue, or purplish patches in the skin
• large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
• loss of heat from the body
• muscle or joint pain
• nosebleeds
• not able to pass urine
• numbness or tingling in the hands, feet, or lips
• pain or burning while urinating
• pinpoint red spots on the skin
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• raised red swellings on the skin, the buttocks, legs, or ankles
• redness of the white part of the eyes
• redness, swelling, or soreness of the tongue
• seizures
• soreness of the muscles
• stiff neck or back
• stomach tenderness
• swelling of the face, hands, legs, and feet
• unsteadiness, trembling, or other problems with muscle control or coordination
• weakness in the hands or feet
• weakness or heaviness of the legs
• weight gain or loss

Other side effects

Some side effects of sulfamethoxazole / trimethoprim may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Denied health insurance claims are a major problem for patients in America. The Kaiser Family Foundation found that ACA marketplace plans denied about 17% of in-network claims in 2019.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Incidence not known

• Discouragement
• feeling of constant movement of self or surroundings
• feeling sad or empty
• increased sensitivity of the skin to sunlight
• lack of feeling or emotion
• loss of interest or pleasure
• muscle pain, stiffness, cramps, or spasms
• nervousness
• redness or other discoloration of the skin
• seeing, hearing, or feeling things that are not there
• sensation of spinning
• severe sunburn
• trouble concentrating
• trouble sleeping
• uncaring
• weight loss

For Healthcare Professionals

Applies to sulfamethoxazole / trimethoprim: intravenous solution, oral suspension, oral tablet.

General

The most common side effects were gastrointestinal disturbances (nausea, vomiting, anorexia) and allergic skin reactions (e.g., rash, urticaria).

Effects associated with Pneumocystis jirovecii pneumonia management have included severe hypersensitivity reactions, rash, pyrexia, neutropenia, thrombocytopenia, elevated liver enzymes, hyperkalemia, hyponatremia, and rhabdomyolysis; such effects were very rare.

Although rare, fatalities associated with sulfonamide use have occurred due to severe reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, other blood dyscrasias, and respiratory hypersensitivity. [Ref]

Metabolic

Very common (10% or more): Hyperkalemia

Frequency not reported: Anorexia, hypoglycemia, hyponatremia, decreased appetite

Hypoglycemia has been reported in patients using sulfonamides. [Ref]

Gastrointestinal

Common (1% to 10%): Nausea, diarrhea

Uncommon (0.1% to 1%): Vomiting

Nervous system

Aseptic meningitis was rapidly reversible when this drug was stopped but recurred in several cases upon re-exposure to either this combination drug or to trimethoprim alone.

Tremor and other neurological manifestations (e.g., ataxia, ankle clonus, apathy) occurred during therapy with this drug in several patients with AIDS; although such effects have also been associated with the underlying disease process, these symptoms resolved within 2 to 3 days after stopping this drug. [Ref]

Common (1% to 10%): Headache

Frequency not reported: Aseptic meningitis, convulsions/seizures, peripheral neuritis/neuropathy, ataxia, dizziness, vertigo, tinnitus, tremor, other neurological manifestations (e.g., ataxia, ankle clonus, apathy), lethargy, paresthesia, syncope [Ref]

Dermatologic

Common (1% to 10%): Rash

Frequency not reported: Diffuse rash, erythematous rash, maculopapular rash, morbilliform rash, pruritic rash, urticaria, photosensitivity, pruritus, exfoliative dermatitis, fixed drug eruption, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, Henoch-Schonlein purpura, drug reaction with eosinophilia and systemic symptoms (DRESS), generalized skin eruptions, purpura, angioedema, generalized pustular dermatosis, alopecia, allergic/hypersensitivity vasculitis resembling Henoch-Schonlein purpura, erythema nodosum, bullous dermatitis [Ref]

Other

Common (1% to 10%): Fungal/monilial overgrowth

Frequency not reported: Drug fever, chills, weakness, fatigue, abnormal elevations in alkaline phosphatase, positive lupus erythematous phenomenon, moniliasis [Ref]

Cardiovascular

Frequency not reported: Thrombophlebitis, allergic myocarditis, polyarteritis/periarteritis nodosa

Postmarketing reports: QT prolongation (resulting in ventricular tachycardia and torsade de pointes) [Ref]

Hematologic

Frequency not reported: Leucopenia, neutropenia, thrombocytopenia, bone marrow depression, agranulocytosis, aplastic anemia, hemolytic anemia, megaloblastic anemia, methemoglobinemia, hypoprothrombinemia, eosinophilia, hematological toxicity, hemolysis, pancytopenia, granulocytopenia

Severe cases of thrombocytopenia that were fatal or life-threatening have been reported. Thrombocytopenia generally resolved within a week when this drug was discontinued.

Hemolysis has been reported in certain susceptible glucose-6-phosphate deficient patients. [Ref]

Hepatic

Frequency not reported: Hepatitis, cholestatic jaundice, hepatic necrosis, elevated serum transaminase, elevated bilirubin, hepatic changes, abnormal elevations in serum transaminase levels, jaundice, elevated liver enzymes, disturbance in liver enzymes [Ref]

Cases of cholestatic jaundice and hepatic necrosis have been fatal.

Jaundice (generally mild and transient) has been reported rarely, often occurring in patients with history of infectious hepatitis. [Ref]

Hypersensitivity

Frequency not reported: Hypersensitivity, allergic skin reactions, anaphylaxis, serum sickness-like syndrome, generalized allergic reactions, anaphylactic/anaphylactoid reactions, severe hypersensitivity reactions (including associated with P jirovecii pneumonia), serum sickness [Ref]

Local

Frequency not reported: Local reaction, pain, slight/local irritation, inflammation [Ref]

Local reaction, pain, and slight irritation were reported infrequently with IV administration. [Ref]

Musculoskeletal

Frequency not reported: Arthralgia, myalgia, rhabdomyolysis, systemic lupus erythematosus, muscle weakness [Ref]

Rhabdomyolysis has been reported with this drug, primarily in patients with AIDS. [Ref]

Ocular

Frequency not reported: Uveitis, conjunctival and scleral injection/redness/edema, periorbital edema, corneal ring infiltrates, vision problems [Ref]

Psychiatric

Frequency not reported: Depression/mental depression, hallucinations, apathy, nervousness, insomnia, psychotic disorder, confusional state, agitation, anxiety, abnormal behavior, nightmares [Ref]

Renal

Nephrotoxicity has been reported in association with cyclosporine. [Ref]

Frequency not reported: Renal impairment/failure, interstitial nephritis, tubulointerstitial nephritis and uveitis syndrome, elevated BUN, elevated serum creatinine, toxic nephrosis, renal tubular acidosis, nephrotoxicity, functional kidney changes, abnormal elevations in serum urea, abnormal elevations in serum creatinine, stone formation, tubular necrosis, aggravation of renal disease, azotemia, hyperkalemic renal tubular acidosis, overestimations of normal creatinine values [Ref]

Genitourinary

Diuresis has been reported in patients using sulfonamides. [Ref]

Frequency not reported: Oliguria, anuria, crystalluria, diuresis, dysuria, hematuria, urgency changes, abnormal elevations in urine protein levels [Ref]

Respiratory

Frequency not reported: Cough, dyspnea/shortness of breath, pulmonary infiltrates/lung infiltration, epistaxis, eosinophilic/allergic alveolitis, wheezing [Ref]

Cough, dyspnea, and lung infiltration have been early indicators of respiratory hypersensitivity which, while very rare, has been fatal. [Ref]

Frequently asked questions

• What drugs should be avoided with a sulfa allergy?
• 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 sulfamethoxazole / trimethoprim

• Check interactions
• Compare alternatives
• Pricing & coupons
• Reviews (1,680)
• Drug images
• Dosage information
• Patient tips
• During pregnancy
• Support group
• Drug class: sulfonamides
• En español

Patient resources

• Drug Information
• Sulfamethoxazole and trimethoprim (Advanced Reading)
• Sulfamethoxazole/trimethoprim Intravenous (Advanced Reading)
• Sulfamethoxazole and Trimethoprim Injection
• Sulfamethoxazole and Trimethoprim Tablets
• Sulfamethoxazole and Trimethoprim Suspension

Other brands

Professional resources

Related treatment guides

• Bacterial Skin Infection
• Bacterial Infection
• Acne
• Bronchitis

References

1. “Product Information. Septra (sulfamethoxazole-trimethoprim).” Glaxo Wellcome (2022):

2. “Product Information. Sulfamethoxazole-Trimethoprim (sulfamethoxazole-trimethoprim).” Teva SICOR Pharmaceuticals Inc (2004):

3. Cerner Multum, Inc. “UK Summary of Product Characteristics.” O 0

4. Cerner Multum, Inc. “Australian Product Information.” O 0

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.

Sulfamethoxazole and trimethoprim

Generic name: sulfamethoxazole and trimethoprim (oral/injection) [ SUL-fa-meth-OX-a-zole-and-trye-METH-oh-prim ]
Brand names: Bactrim, Bactrim DS, SMZ-TMP DS, Sulfatrim Pediatric, Septra, . show all 18 brands Sulfatrim, Bethaprim, Cotrim, Uroplus, Uroplus DS, Cotrim DS, Septra I.V., Bactrim I.V., Bactrim Pediatric, Bethaprim Pediatric, Sulfatrim Suspension, Cotrim Pediatric, Septra DS
Dosage forms: intravenous solution (80 mg-16 mg/mL); oral suspension (200 mg-40 mg/5 mL); oral tablet (400 mg-80 mg; 800 mg-160 mg)
Drug class: Sulfonamides

Medically reviewed by Drugs.com on Aug 30, 2021. Written by Cerner Multum.

What is sulfamethoxazole and trimethoprim?

Sulfamethoxazole and trimethoprim is a combination antibiotic used to treat ear infections, urinary tract infections, bronchitis, traveler’s diarrhea, shigellosis, and Pneumocystis jiroveci pneumonia.

Sulfamethoxazole and trimethoprim may also be used for purposes not listed in this medication guide.

Warnings

Use only as directed. Tell your doctor if you use other medicines or have other medical conditions or allergies.

Before taking this medicine

You should not use sulfamethoxazole and trimethoprim 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.

May cause birth defects. Do not use if you are pregnant. Tell your doctor if you become pregnant.

Do not breastfeed.

This medicine should not be given to a child younger than 2 months old.

Tell your doctor if you have ever had:

• kidney or liver disease;
• a folate (folic acid) deficiency;
• asthma or severe allergies;
• HIV or AIDS;
• a thyroid disorder;
• malnourishment;
• alcoholism;
• an electrolyte imbalance (such as low blood sodium or high potassium);
• 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 use sulfamethoxazole and trimethoprim?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Sulfamethoxazole and trimethoprim oral is taken by mouth.

Shake the oral suspension (liquid). Measure a dose with the supplied measuring device (not a kitchen spoon).

Sulfamethoxazole and trimethoprim injection is given in a vein. Be sure you understand how to properly mix this medicine with a liquid (diluent) and how to store the mixture. Ask your doctor or pharmacist if you don’t understand how to use an injection.

Prepare an injection only when you are ready to give it. Call your pharmacist if the medicine looks cloudy, has changed colors, or has particles in it.

Mixed medicine must be used within 2 to 6 hours depending on the amount of diluent in the mixture. Follow your doctor’s instructions. Do not refrigerate mixed medicine.

Do not reuse a needle or syringe. Place them in a puncture-proof “sharps” container and dispose of it following state or local laws. Keep out of the reach of children and pets.

Drink plenty of fluids to prevent kidney stones.

Antibiotic medicines can cause diarrhea. Tell your doctor if you have diarrhea that is watery or bloody.

Keep using this medicine even if your symptoms quickly improve. Skipping doses could make your infection resistant to medication. Sulfamethoxazole and trimethoprim will not treat a viral infection (flu or a common cold).

You may need blood and urine tests, and this medicine may be stopped based on the results.

Store at room temperature away from moisture, heat, and light. Do not refrigerate.

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 sulfamethoxazole and trimethoprim?

If you use the injection form of sulfamethoxazole and trimethoprim, do not eat or drink anything that contains propylene glycol (an ingredient in many processed foods, soft drinks, and medicines). Dangerous effects could occur.

Sulfamethoxazole and trimethoprim 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.

Sulfamethoxazole and trimethoprim side effects

Get emergency medical help if you have signs of an allergic reaction (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.

Sulfamethoxazole and trimethoprim may cause serious side effects. 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);
• any skin rash, no matter how mild;
• yellowing of your skin or eyes;
• a seizure;
• 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 blood potassium–nausea, weakness, tingly feeling, chest pain, irregular heartbeats, loss of movement;
• low blood sodium–headache, confusion, problems with thinking or memory, weakness, 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 side effects of sulfamethoxazole and trimethoprim may include:

• nausea, vomiting, loss of appetite; or
• skin rash.

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 sulfamethoxazole and trimethoprim?

You may need more frequent check-ups or medical tests if you also use medicine to treat depression, diabetes, seizures, or HIV.

Tell your doctor about all your current medicines. Many drugs can affect sulfamethoxazole and trimethoprim, especially:

• amantadine, digoxin, cyclosporine, indomethacin, leucovorin, methotrexate, procainamide, pyrimethamine;
• an “ACE inhibitor” heart or blood presure medication (benazepril, enalapril, lisinopril, quinapril, ramipril, and others); or
• a diuretic or “water pill”.

This list is not complete and many other drugs may affect sulfamethoxazole and trimethoprim. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Where can I get more information?

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Popular FAQ

People with a sulfa allergy typically need to avoid sulfonamide antibiotics (antibiotics containing sulfa), including:

• Septra and Bactrim (sulfamethoxazole-trimethoprim)
• Pediazole (erythromycin-sulfisoxazole)

Whether other nonantibiotic sulfa-containing drugs need to be avoided with sulfa allergy is unclear and considered on a case-by-case basis. Continue reading

More FAQ

• 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 sulfamethoxazole / trimethoprim

• Check interactions
• Compare alternatives
• Pricing & coupons
• Reviews (1,680)
• Drug images
• Side effects
• Dosage information
• Patient tips
• During pregnancy
• Support group
• Drug class: sulfonamides
• En español

Patient resources

• Advanced Reading
• Sulfamethoxazole/trimethoprim Intravenous (Advanced Reading)
• Sulfamethoxazole and Trimethoprim Injection
• Sulfamethoxazole and Trimethoprim Tablets
• Sulfamethoxazole and Trimethoprim Suspension

Other brands

Professional resources

Related treatment guides

• Bacterial Skin Infection
• Bacterial Infection
• Acne
• Bronchitis

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2023 Cerner Multum, Inc. Version: 11.02.