sulfamethoxazole and trimethoprim

Generic Name: sulfamethoxazole and trimethoprim (SUL fa meth OX a zole and trye METH oh prim)
Brand Name: Bactrim, Bactrim DS, Septra, Septra DS, SMZ-TMP DS, Sulfatrim Pediatric, ...show all 18 brand namesSulfatrim, Bethaprim, Cotrim, Uroplus, Uroplus DS, Cotrim DS, Septra I.V., Bactrim I.V., Bactrim Pediatric, Bethaprim Pediatric, Sulfatrim Suspension, Cotrim Pediatric

What is sulfamethoxazole and trimethoprim?

Sulfamethoxazole and trimethoprim are both antibiotics that treat different types of infection caused by bacteria.

The combination of sulfamethoxazole and trimethoprim is 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.

What is the most important information I should know about sulfamethoxazole and trimethoprim?

You should not use this medication if you are allergic to sulfamethoxazole or trimethoprim, if you are pregnant or breast-feeding, or if you have anemia (lack of red blood cells) caused by folic acid deficiency.

Before using this medication, tell your doctor if you have kidney or liver disease, a folic acid deficiency, asthma or severe allergies, a thyroid disorder, HIV or AIDS, porphyria, G6PD deficiency, or if you are malnourished.

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Take this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Sulfamethoxazole and trimethoprim will not treat a viral infection such as the common cold or flu.

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or has blood in it, call your doctor. Do not use any medicine to stop the diarrhea unless your doctor has told you to.

Avoid exposure to sunlight or tanning beds. This medication can make you sunburn more easily. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

What should I discuss with my healthcare provider before taking sulfamethoxazole and trimethoprim?

You should not use this medication if you are allergic to sulfamethoxazole or trimethoprim, if you are pregnant or breast-feeding, or if you have anemia (lack of red blood cells) caused by folic acid deficiency.

To make sure this medication is safe for you, tell your doctor if you have any of these other conditions:

• kidney or liver disease;

• a folic acid deficiency;

• asthma or severe allergies;

• a thyroid disorder;

• HIV or AIDS;

• porphyria (a genetic enzyme disorder that causes symptoms affecting the skin or nervous system);

• a glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency); or

• if you are malnourished.

FDA pregnancy category C. It is not known whether sulfamethoxazole and trimethoprim will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

Sulfamethoxazole and trimethoprim can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

Do not give this medication to a child younger than 2 months old.

Older adults may be more likely to have side effects from this medicine.

How should I take sulfamethoxazole and trimethoprim?

Take exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.

Measure liquid medicine with a special dose-measuring spoon or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.

Take this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Sulfamethoxazole and trimethoprim will not treat a viral infection such as the common cold or flu.

Drink plenty of fluids to prevent kidney stones while you are taking trimethoprim and sulfamethoxazole.

This medication can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using sulfamethoxazole and trimethoprim.

Store at room temperature away from moisture, heat, and light.

See also: Sulfamethoxazole and trimethoprim dosage (in more detail)

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include severe forms of some of the side effects listed in this medication guide.

What should I avoid while taking sulfamethoxazole and trimethoprim?

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, stop taking this medication and call your doctor. Do not use anti-diarrhea medicine unless your doctor tells you to.

Avoid exposure to sunlight or tanning beds. This medication can make you sunburn more easily. 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 any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

• diarrhea that is watery or bloody;

• fever, chills, swollen glands, body aches, flu symptoms, sores in your mouth and throat;

• new or worsening cough;

• pale skin, feeling light-headed, rapid heart rate, trouble concentrating;

• easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;

• severe tingling or numbness, slow heart rate, weak pulse, muscle weakness;

• nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

• urinating less than usual or not at all;

• hallucinations, seizure (convulsions);

• low blood sugar (headache, hunger, weakness, sweating, confusion, irritability, or feeling jittery);

• the first sign of any skin rash, no matter how mild; or

• severe skin reaction -- fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Less serious side effects may include:

• vomiting;

• painful or swollen tongue;

• dizziness, spinning sensation;

• ringing in your ears; or

• tired feeling, sleep problems (insomnia).

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.

See also: sulfamethoxazole and trimethoprim side effects (in more detail)

Sulfamethoxazole and trimethoprim Dosing Information

Usual Adult Dose for Pneumocystis Pneumonia:

15 to 20 mg/kg/day (trimethoprim component) orally or IV in 3 to 4 equally divided doses every 6 to 8 hours; according to 1 investigator, 10 to 15 mg/kg/day (trimethoprim component) IV was sufficient in 10 patients

Duration: 14 to 21 days; treatment should be followed by chronic suppressive therapy

If the patient is hypoxemic, IV therapy is recommended. Oral therapy may be substituted once the patient is able to tolerate oral medications and improves clinically. During oral therapy, desirable sulfamethoxazole levels are 100 to 150 mcg/mL. Levels exceeding 200 mcg/mL are associated with more side effects. Trimethoprim levels should be maintained between 5 to 8 mcg/mL.

Usual Adult Dose for Pneumocystis Pneumonia Prophylaxis:

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally once a day or 3 times a week

The dose should be doubled to 2 tablets if the patient has latently infected toxoplasmosis.

Duration: Therapy should be continued for as long as the patient is at risk for infection. Most experts implement prophylaxis as long as the CD4 count is less than 200 or the CD4% is less than 15% in HIV-infected patients, for at least 1 year in transplant patients, and indefinitely for lung transplant patients and patients with recurrent rejection.

Usual Adult Dose for Urinary Tract Infection:

Oral: Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours for 10 to 14 days

IV:
Severe infection: 8 to 10 mg/kg/day (trimethoprim component) IV in 2 to 4 equally divided doses every 6, 8, or 12 hours for up to 14 days; maximum recommended dose is 960 mg (trimethoprim component) per day

Usual Adult Dose for Pyelonephritis:

Uncomplicated: Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours for 7 to 14 days

Usual Adult Dose for Bronchitis:

Acute bacterial exacerbation of chronic bronchitis: Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours for 14 days

Usual Adult Dose for Traveler's Diarrhea:

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours for 5 days

Usual Adult Dose for Shigellosis:

Oral: Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours for 5 days

IV: 8 to 10 mg/kg/day (trimethoprim component) IV in 2 to 4 equally divided doses every 6, 8, or 12 hours for 5 days; maximum recommended dose is 960 mg (trimethoprim component) per day

The patient should be instructed to use extraordinary sanitary precautions since Shigella is transmitted by the fecal-oral route, primarily by hand-to-mouth contact.

Usual Adult Dose for Otitis Media:

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours for 10 to 14 days

Usual Adult Dose for Cystitis Prophylaxis:

Trimethoprim-sulfamethoxazole 80 mg-400 mg (1 single-strength tablet) orally once a day or 3 times a week at bedtime

Some clinicians recommend that their female patients take this low dose postcoitally or 3 times a week, whichever is less frequent. Therapy should be continued for as long as the patient is at risk for infection.

Usual Adult Dose for Diverticulitis:

Mild, outpatient: Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours in combination with metronidazole 500 mg orally every 6 hours

Duration: 7 to 10 days

Usual Adult Dose for Epiglottitis:

2.5 mg/kg (trimethoprim component) IV every 6 hours
or
3.3 mg/kg (trimethoprim component) IV every 8 hours
or
5 mg/kg (trimethoprim component) IV every 12 hours

Oral therapy may be substituted once the patient improves and is able to tolerate oral medication.

Usual Adult Dose for Granuloma Inguinale:

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally twice a day for at least 3 weeks

Usual Adult Dose for Infection Prophylaxis:

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally twice a day

Duration: Therapy is usually continued as long as there is risk of infection. Patients with neutropenia are usually treated until they are afebrile for 24 hours and the absolute neutrophil count is greater than 500 cells/mm3. Routine prophylaxis is generally not recommended for granulocytic patients unless they are at risk for Pneumocystis pneumonitis.

Usual Adult Dose for Melioidosis:

After an initial 10 days of parenteral therapy with ceftazidime, imipenem, or meropenem: 5 mg/kg (trimethoprim component) orally twice a day plus doxycycline 100 mg orally twice a day plus chloramphenicol 10 mg/kg orally (not available in the United States) four times a day

Duration: Trimethoprim-sulfamethoxazole and doxycycline for 20 weeks; chloramphenicol for the first 8 weeks

Usual Adult Dose for Meningitis:

5 mg/kg (trimethoprim component) IV every 6, 8, or 12 hours for 21 days to 6 weeks

Use in combination with chloramphenicol is an alternative for patients with beta-lactam allergy.

Usual Adult Dose for Nocardiosis:

Cutaneous infection: 5 to 10 mg/kg/day (trimethoprim component) IV or orally in 2 to 4 divided doses

Severe infection (pulmonary/cerebral): 15 mg/kg/day (trimethoprim component) in 2 to 4 divided doses for 3 to 4 weeks, then 10 mg/kg/day (trimethoprim component) in 2 to 4 divided doses; may be initiated IV and converted to oral therapy (frequently converted to approximate dosages of oral solid dosage forms: 2 double-strength tablets [320 mg-1600 mg] every 8 to 12 hours)

Measurement of serum levels is advisable. Maximum plasma concentrations (Cmax) of 100 to 150 mcg/mL are recommended. Severe disease is often treated with addition of other agents, such as ceftriaxone, imipenem, or amikacin.

Duration: Not well standardized; most experts recommend at least 6 months for local disease in immunocompetent patients and 6 to 12 months or more for immunocompromised patients or patients with CNS disease

Usual Adult Dose for Pneumonia:

2.5 mg/kg (trimethoprim component) orally or IV every 6 hours
or
3.3 mg/kg (trimethoprim component) orally or IV every 8 hours
or
5 mg/kg (trimethoprim component) orally or IV every 12 hours

Duration: 21 days; pneumococcal pneumonia may be completely treated in 7 to 10 days

Usual Adult Dose for Prostatitis:

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours

Duration: Acute, 10 to 14 days; chronic, 1 to 3 months

Usual Adult Dose for Sinusitis:

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours

Duration: 10 to 14 days; in some cases of recurrent or refractory sinusitis, therapy may be required for up to 3 to 4 weeks

Usual Adult Dose for Toxoplasmosis:

5 mg/kg (trimethoprim component) IV every 12 hours

Duration: 4 weeks to 6 months or more, depending on the nature and severity of the infection; patients with AIDS are usually given high dose therapy for 4 to 6 weeks then maintained on oral trimethoprim-sulfamethoxazole for life

Usual Adult Dose for Toxoplasmosis -- Prophylaxis:

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) or 80 mg-400 mg (1 single-strength tablet) orally once a day

Duration: Therapy should be continued for as long as the patient is at risk for infection.

Usual Adult Dose for Upper Respiratory Tract Infection:

Trimethoprim-sulfamethoxazole 160 mg-800 mg (1 double-strength tablet) orally every 12 hours

Usual Pediatric Dose for Otitis Media:

2 months or older: 4 mg/kg (trimethoprim component) orally every 12 hours for 10 days

Usual Pediatric Dose for Urinary Tract Infection:

2 months or older:
Oral: 4 mg/kg (trimethoprim component) orally every 12 hours for 10 to 14 days

IV:
Severe infection: 8 to 10 mg/kg/day (trimethoprim component) IV in 2 to 4 equally divided doses every 6, 8, or 12 hours for up to 14 days; maximum recommended dose is 960 mg (trimethoprim component) per day

Usual Pediatric Dose for Shigellosis:

2 months or older:
Oral: 4 mg/kg (trimethoprim component) orally every 12 hours for 5 days

IV: 8 to 10 mg/kg/day (trimethoprim component) IV in 2 to 4 equally divided doses every 6, 8, or 12 hours for 5 days; maximum recommended dose is 960 mg (trimethoprim component) per day

Usual Pediatric Dose for Pneumocystis Pneumonia:

2 months or older: 15 to 20 mg/kg/day (trimethoprim component) orally or IV in 3 to 4 equally divided doses every 6 to 8 hours for 14 to 21 days

Usual Pediatric Dose for Pneumocystis Pneumonia Prophylaxis:

2 months or older: 75 mg/m2 (trimethoprim component) orally twice a day, on 3 consecutive days per week

The total daily dose should not exceed 320 mg (trimethoprim component).

What other drugs will affect sulfamethoxazole and trimethoprim?

Tell your doctor about all other medications you use, especially:

• an antidepressant;

• a blood thinner such as warfarin (Coumadin, Jantoven);

• cyclosporine (Gengraf, Neoral, Sandimmune);

• oral diabetes medication;

• digoxin (Lanoxin, Lanoxicaps);

• a diuretic (water pill);

• indomethacin (Indocin);

• leucovorin, calcium folinate;

• methotrexate (Trexall, Rheumatrex);

• heart or blood pressure medication such as benazepril (Lotensin), captopril (Capoten), fosinopril (Monopril), enalapril (Vasotec), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), or trandolapril (Mavik).

• seizure medication such as phenytoin (Dilantin);

This list is not complete and other drugs may interact with sulfamethoxazole and trimethoprim. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.

Where can I get more information?

• Your pharmacist can provide more information about sulfamethoxazole and trimethoprim.