Sulfamethoxazole + Trimethoprim

By Medically reviewed by hellodoktor

Generic Name: Sulfamethoxazole + Trimethoprim Brand Name(s): Sulfamethoxazole + Trimethoprim.

Uses

What is Sulfamethoxazole + Trimethoprim used for?

Sulfamethoxazole + Trimethoprim is a combination of two antibiotics: sulfamethoxazole and trimethoprim. It is used to treat a wide variety of bacterial infections (such as middle ear, urine, respiratory, and intestinal infections). It is also used to prevent and treat a certain type of pneumonia (pneumocystis-type).

This medication should not be used in children less than 2 months of age due to the risk of serious side effects.

This medication treats only certain types of infections. It will not work for viral infections (such as flu). Unnecessary use or misuse of any antibiotic can lead to its decreased effectiveness.

How should I take Sulfamethoxazole + Trimethoprim?

Shake this medication well before each dose. Carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose. Take this medication by mouth, as directed by your doctor, with a full glass of water (8 ounces / 240 milliliters). If stomach upset occurs, take with food or milk. Drink plenty of fluids while taking this medication to lower the unlikely risk of kidney stones forming, unless your doctor advises you otherwise. Dosage is based on your medical condition and response to treatment.

For the best effect, take this antibiotic at evenly spaced times. To help you remember, take this medication at the same time(s) every day.

Continue to take this medication until the full prescribed amount is finished, even if symptoms disappear after a few days. Stopping it too early may allow bacteria to continue to grow, which may result in a relapse of the infection.

Tell your doctor if your condition persists or worsens.

How do I store Sulfamethoxazole + Trimethoprim?

Sulfamethoxazole + Trimethoprim is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Sulfamethoxazole + Trimethoprim in the bathroom or the freezer. There may be different brands of Sulfamethoxazole + Trimethoprim that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Sulfamethoxazole + Trimethoprim down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Sulfamethoxazole + Trimethoprim?

Before taking sulfamethoxazole with trimethoprim, tell your doctor or pharmacist if you are allergic to sulfa medications or trimethoprim; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease, liver disease, certain blood disorders (such as porphyria, anemia due to folate vitamin deficiency), history of blood disorders caused by trimethoprim or sulfa medications, vitamin deficiency (folate or folic acid), severe allergies, asthma, decreased bone marrow function (bone marrow suppression), a certain metabolic disorder (G6PD deficiency), underactive thyroid, mineral imbalances (such as high level of potassium or low level of sodium in the blood).

This medication may cause live bacterial vaccines (such as typhoid vaccine) to not work as well. Do not have any immunizations/vaccinations while using this medication unless your doctor tells you to.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Get medical help right away if you get sunburned or have skin blisters/redness.

If you have diabetes, this product may affect your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms of low blood sugar (see Side Effects section). Your doctor may need to adjust your diabetes medication, exercise program, or diet.

Older adults may be more sensitive to the side effects of this drug, especially skin reactions, blood disorders, easy bleeding/bruising, and a high potassium blood level.

Patients with AIDS may be more sensitive to the side effects of this drug, especially skin reactions, fever, and blood disorders.

This medication is not recommended for use during pregnancy especially near the expected delivery date because of possible harm to the unborn baby. Consult your doctor for more details.

This drug passes into breast milk. While there have been no reports of harm to healthy infants, this drug may have undesirable effects on infants who are ill or premature or have certain disorders (jaundice, high blood levels of bilirubin, G6PD deficiency). Therefore, breast-feeding is not recommended for infants with these conditions. Consult your doctor before breast-feeding.

Is it safe during pregnancy or breast-feeding?

There are no adequate studies in women for determining risk when using this Sulfamethoxazole + Trimethoprim during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking Sulfamethoxazole + Trimethoprim. Sulfamethoxazole + Trimethoprim is pregnancy risk category D according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk,
  • B=No risk in some studies,
  • C=There may be some risk,
  • D=Positive evidence of risk,
  • X=Contraindicated,
  • N=Unknown

Side effects

What side effects can occur from Sulfamethoxazole + Trimethoprim?

Nausea, vomiting, diarrhea, and loss of appetite may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including: muscle weakness, mental/mood changes, signs of kidney problems (such as change in the amount of urine, blood in the urine), extreme drowsiness, signs of low blood sugar (such as sudden sweating, shaking, fast heartbeat, hunger, blurred vision, dizziness, or tingling hands/feet).

Get medical help right away if you have any very serious side effects, including: persistent headache, neck stiffness, seizures, slow/irregular heartbeat.

This medication may rarely cause serious (possibly fatal) allergic reactions and other side effects such as a severe peeling skin rash (such as Stevens-Johnson syndrome), blood disorders (such as agranulocytosis, aplastic anemia), liver damage, or lung injury. If you notice any of the following, get medical help right away: skin rash/blisters, itching/swelling (especially of the face/tongue/throat), persistent sore throat or fever, paleness, joint pain/aches, persistent cough, trouble breathing, easy bleeding/bruising, yellowing eyes or skin, persistent nausea/vomiting, unusual fatigue, dark urine.

This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to a type of resistant bacteria. This condition may occur during treatment or weeks to months after treatment has stopped. Tell your doctor right away if you develop: persistent diarrhea, abdominal or stomach pain/cramping, blood/mucus in your stool.

Do not use anti-diarrhea products or narcotic pain medications if you have any of these symptoms because these products may make them worse.

Use of this medication for prolonged or repeated periods may result in oral thrush or a new yeast infection. Contact your doctor if you notice white patches in your mouth, a change in vaginal discharge, or other new symptoms.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with Sulfamethoxazole + Trimethoprim?

Some products that may interact with this drug include: “blood thinners” (such as warfarin), dofetilide, methenamine, methotrexate.

Although most antibiotics are unlikely to affect hormonal birth control such as pills, patch, or ring, a few antibiotics (such as rifampin, rifabutin) can decrease their effectiveness. This could result in pregnancy. If you use hormonal birth control, ask your doctor or pharmacist for more details.

This product may interfere with certain laboratory tests, possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this product.

Sulfamethoxazole + Trimethoprim may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with Sulfamethoxazole + Trimethoprim?

Sulfamethoxazole + Trimethoprim may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Sulfamethoxazole + Trimethoprim?

Sulfamethoxazole + Trimethoprim may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this Sulfamethoxazole + Trimethoprim.

What is the dose of Sulfamethoxazole + Trimethoprim for an adult?

Usual Adult Dose for Pneumocystis Pneumonia

Oral: 15 to 20 mg/kg/day (based on the trimethoprim component) orally daily in 4 equally divided doses every 6 hours for 14 to 21 days

IV: 15 to 20 mg/kg/day (based on the trimethoprim component) IV daily in 3 or 4 equally divided doses every 6 to 8 hours for up to 14 days

Comments:

-IV formulation: One investigator noted that a total daily dose of 10 to 15 mg/kg was sufficient in 10 adult patients with normal renal function.

Use: For the treatment of documented Pneumocystis jiroveci pneumonia

Usual Adult Dose for Pneumocystis Pneumonia Prophylaxis

-Sulfamethoxazole-trimethoprim 800 mg-160 mg (1 double strength tablet) orally once a day

-Maximum dose: The total daily dose should not exceed 1600 mg sulfamethoxazole and 320 mg trimethoprim

Use: For prophylaxis against P jiroveci pneumonia in individuals who are immunosuppressed and considered to be at an increased risk of developing P jiroveci pneumonia

Usual Adult Dose for Urinary Tract Infection

Oral: Sulfamethoxazole-trimethoprim 800 mg-160 mg orally every 12 hours for 10 to 14 days

IV:

Severe infection: 8 to 10 mg/kg/day (based on the 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 (based on the trimethoprim component) per day

Use: For the treatment of severe or complicated urinary tract infections due to susceptible strains of Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis, and Proteus vulgaris

Usual Adult Dose for Shigellosis

Oral: Sulfamethoxazole-trimethoprim 800 mg-160 mg (1 double strength tablet or 2 single strength tablets) orally every 12 hours for 5 days

IV:

Severe infection: 8 to 10 mg/kg/day (based on the 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 (based on the trimethoprim component) per day

Comments:

-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.

Use: For the treatment of enteritis caused by susceptible strains of Shigella flexneri and Shigella sonnei

Usual Adult Dose for Bronchitis

Sulfamethoxazole-trimethoprim 800 mg-160 mg (1 double strength tablet or 2 single strength tablets) orally every 12 hours for 14 days

Use: For acute exacerbations of chronic bronchitis due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae when the physician deems that sulfamethoxazole and trimethoprim could offer some advantage over the use of a single antimicrobial agent

Usual Adult Dose for Traveler’s Diarrhea

Sulfamethoxazole-trimethoprim 800 mg-160 mg (1 double strength tablet or 2 single strength tablets) orally every 12 hours for 5 days

Use: For the treatment of traveler’s diarrhea due to susceptible strains of enterotoxigenic E coli

Usual Adult Dose for Pyelonephritis

Uncomplicated: Sulfamethoxazole-trimethoprim 800 mg-160 mg (1 double strength tablet) orally every 12 hours for 10 days

Use: Uncomplicated pyelonephritis (off-label use)

Usual Adult Dose for Otitis Media

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

Use: Otitis media (off-label use in adults)

Usual Adult Dose for Cystitis Prophylaxis

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

Comments:

-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.

Use: Cystitis prophylaxis (off-label use)

Usual Adult Dose for Granuloma Inguinale

Sulfamethoxazole-trimethoprim 800 mg-160 mg (1 double strength tablet) orally 2 times a day for at least 3 weeks

Use: Granuloma inguinale (off-label use)

Usual Adult Dose for Meningitis

10 to 20 mg/kg (based on the trimethoprim component) IV every 6 to 12 hours

Comments:

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

Use: Bacterial meningitis (off-label use)

Usual Adult Dose for Nocardiosis

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

Severe infection (pulmonary/cerebral): 15 mg/kg/day (based on the trimethoprim component) in 2 to 4 divided doses for 3 to 4 weeks, then 10 mg/kg/day (based on the 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)

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

Comments:

-Off-label use.

-Measurement of serum levels are 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.

Usual Adult Dose for Prostatitis

Sulfamethoxazole-trimethoprim 800 mg-160 mg (1 double strength tablet) orally every 12 hours

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

Comments:

-Off-label use.

Usual Adult Dose for Sinusitis

Sulfamethoxazole-trimethoprim 800 mg-160 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

Comments:

-Off-label use.

Usual Adult Dose for Toxoplasmosis

5 mg/kg (based on the 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

Comments:

-Off-label use.

Usual Adult Dose for Toxoplasmosis – Prophylaxis

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 Upper Respiratory Tract Infection

Sulfamethoxazole-trimethoprim 800 mg-160 mg (1 double strength tablet) orally every 12 hours

Comments:

-Off-label use.

Renal Dose Adjustments

CrCl less than 15 mL/min: Contraindicated

CrCl 15 to 30 mL/min: Reduce dose by 50%.

CrCl greater than 30 mL/min: Use standard dosing.

Liver Dose Adjustments

Severe hepatic impairment: Contraindicated

Mild to moderate hepatic impairment: Caution is recommended.

Dose Adjustments

IV administration should be restricted to use during periods in which the patient is unable to accept oral therapy.

Dialysis

Peritoneal dialysis is not effective and hemodialysis is only moderately effective in eliminating trimethoprim (TMP) and sulfamethoxazole (SMX). Because both TMP and SMX are moderately removed by hemodialysis, it is recommended that the combination drug be given after dialysis sessions if doses are scheduled to be given on the days the patient is dialyzed.

Other Comments

Administration advice:

-The oral formulation should be administered with food and/or liquids.

-Adequate fluid intake and urinary output should be maintained to prevent crystalluria.

-Oral syrup is recommended for use in children; the oral tablets are not considered suitable for children under 12 years of age.

General:

-Sulfonamides should not be used for the treatment of infections due to Group A beta-hemolytic streptococci because the organisms may not be eradicated.

-Not all products are approved for the same indications. Refer to the manufacturer product information for indications.

Reconstitution/preparation techniques:

-The IV formulation should be diluted prior to infusion.

Storage requirements:

-The concentrate injection ampules should be stored below 30 degrees Celsius but not refrigerated.

-The diluted solution for IV infusion should be used as soon as possible after preparation and within 24 hours.

-The prepared solution should not be refrigerated.

-The reconstituted IV formulation should be discarded if it has been stored at low temperatures due to the potential for precipitation.

IV compatibility:

-The manufacturer product information should be consulted.

Monitoring:

-Urine analysis and renal function tests should be performed during long term therapy, particularly in patients with reduced renal function.

-Regular blood counts are advisable in patients on long-term therapy, in those predisposed to folate deficiency, in malabsorption syndromes, malnutrition states, or during the treatment of epilepsy with anticonvulsant drugs.

IV compatibility:

-The manufacturer product information should be consulted.

What is the dose of Sulfamethoxazole + Trimethoprim for a child?

Usual Pediatric Dose for Otitis Media

2 months or older:

4 mg/kg (based on the trimethoprim component) orally every 12 hours for 10 to 14 days

Use: For the treatment of acute otitis media in pediatric patients due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae when in the judgment of the physician sulfamethoxazole and trimethoprim offers some advantage over the use of other antimicrobial agents; sulfamethoxazole and trimethoprim is not indicated for prophylactic or prolonged administration in otitis media

Usual Pediatric Dose for Urinary Tract Infection

2 months or older:

-Oral: 4 mg/kg (based on the trimethoprim component) orally every 12 hours for 10 to 14 days

-IV:

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

Use: For the treatment of severe or complicated urinary tract infections due to susceptible strains of Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis, and Proteus vulgaris

Usual Pediatric Dose for Shigellosis

2 months or older:

-Oral: 4 mg/kg (based on the trimethoprim component) orally every 12 hours for 5 days

-IV:

Severe infection: 8 to 10 mg/kg/day (based on the 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 (based on the trimethoprim component) per day

Comments:

-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.

Use: For the treatment of enteritis caused by susceptible strains of Shigella flexneri and Shigella sonnei

Usual Pediatric Dose for Pneumocystis Pneumonia

2 months or older:

15 to 20 mg/kg/day (based on the trimethoprim component) orally or IV every 24 hours given in 4 equally divided doses every 6 hours for 14 to 21 days

Use: For the treatment of documented Pneumocystis jiroveci pneumonia

Usual Pediatric Dose for Pneumocystis Pneumonia Prophylaxis

2 months or older:

75 mg/m2 (based on the trimethoprim component) orally 2 times a day, on 3 consecutive days per week

Maximum dose: The total daily dose should not exceed 320 mg (based on the trimethoprim component)

Use: For prophylaxis against P. jiroveci pneumonia in individuals who are immunosuppressed and considered to be at an increased risk of developing P jiroveci pneumonia

Precautions

Safety and efficacy have not been established in patients younger than 2 months of age.

How is Sulfamethoxazole + Trimethoprim available?

Sulfamethoxazole + Trimethoprim is available in the following dosage forms and strengths:

  • Oral tablet,
  • Oral suspension,
  • Intravenous solution.

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Sulfamethoxazole + Trimethoprim, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: June 1, 2018 | Last Modified: September 12, 2019

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