Bactrim and Bactrim DS are brand-name oral tablets prescribed for certain infections. Bactrim and Bactrim DS contain the active ingredients sulfamethoxazole and trimethoprim.

In certain situations, Bactrim and Bactrim DS are approved by the Food and Drug Administration (FDA) to:

* Doctors may prescribe an oral suspension (liquid) form of this medication for adults and children who cannot swallow oral tablets. However, the brand-name Bactrim suspension is no longer available, but generic versions are available. This article focuses on Bactrim and Bactrim DS, which only come as oral tablets. For more information about generic sulfamethoxazole/trimethoprim oral suspension, talk with your doctor or pharmacist.

Drug details

You’ll find key information about Bactrim and Bactrim DS below.

  • Drug class: sulfonamide antibiotic/antimicrobial
  • Drug form: oral tablet
  • Generic available? yes
  • Prescription required? yes
  • Controlled substance? no
  • Year of FDA approval: 1973

Bactrim and Bactrim DS are brand-name drugs that contain a combination of two active ingredients: sulfamethoxazole and trimethoprim. Sulfamethoxazole/trimethoprim is also available as a generic medication. Generic drugs contain the same active ingredients as the brand-name medication.

The generic is considered to be as safe and effective as the original drug. Generics tend to cost less than brand-name drugs.

If you’re interested in using a generic form of Bactrim or Bactrim DS, talk with your doctor.

Bactrim and Bactrim DS can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Bactrim and Bactrim DS. These lists do not include all possible side effects.

For more information about the possible side effects of Bactrim and Bactrim DS, talk with your doctor or pharmacist. They can give you tips on how to manage any side effects that may concern or bother you.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Bactrim and Bactrim DS, you can do so through MedWatch.

Mild side effects

Below is a partial list of mild side effects of Bactrim and Bactrim DS. To learn about other mild side effects, talk with your doctor or pharmacistd or view the prescribing information for Bactrim and Bactrim DS.

Mild side effects of Bactrim and Bactrim DS can include:

Most of these side effects may go away within a few days to a couple of weeks. However, if they become more severe or don’t go away, talk with your doctor or pharmacist.

* For more information about allergic reaction and Bactrim, see “Allergic reaction” below.

Serious side effects

Serious side effects from Bactrim and Bactrim DS aren’t common, but they can occur. Call your doctor right away if you have serious side effects. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

  • Kidney problems. Signs and symptoms may include:
    • urinating more or less than usual
    • fluid retention
    • blood in your urine
    • urine tests showing crystals in the urine, which may lead to the formation of kidney stones
  • Liver problems, such as hepatitis (inflammation of the liver). Symptoms may include:
  • diarrhea associated with Clostridioides difficile. Symptoms can include:
  • Blood disorders, such as thrombocytopenia (low platelet count). Symptoms may include:
    • bruising easily
    • bleeding
  • Electrolyte imbalances, such as high levels of potassium in your blood. Symptoms of high potassium may include:
  • Tinnitus. Symptoms can include:
    • hearing a ringing, buzzing, or whistling sound in one or both ears
  • Severe allergic reactions,* including serious skin reactions such as Stevens-Johnson syndrome (SJS).

* For details about allergic reaction and Bactrim, see “Allergic reaction” below.

Side effects in children

Children taking Bactrim or Bactrim DS may experience the same side effects as adults taking the medication.

Note that doctors do not prescribe Bactrim or Bactrim DS for children under the age of 2 months.

ALLERGIC REACTION

As with most drugs, some people can have an allergic reaction after taking Bactrim or Bactrim DS. This was a common side effect in clinical trials.

Symptoms of a mild allergic reaction can include:

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • trouble breathing

Call your doctor right away if you have an allergic reaction to Bactrim, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

The Food and Drug Administration (FDA) approves prescription drugs such as Bactrim and Bactrim DS to treat certain conditions. Bactrim may also be used off-label for other conditions. Off-label drug use is when an FDA-approved drug is prescribed for a purpose other than what it’s approved for.

Bactrim for urinary tract infections (UTI)

Bactrim and Bactrim DS are FDA-approved to treat UTIs in adults and children ages 2 months and older.

Symptoms of a UTI often include changes in urination, such as frequent or sudden need to urinate and pain or burning sensation while urinating.

Specifically, Bactrim and Bactrim DS are approved to treat UTIs caused by the following types of bacteria:

  • Escherichia coli
  • Klebsiella species
  • Enterobacter species
  • Morganella morganii
  • Proteus mirabilis
  • Proteus vulgaris

Your doctor may test your urine to check whether this medication is likely to be effective for managing your UTI.

Bactrim for acute otitis media

Bactrim and Bactrim DS are FDA-approved to treat middle ear infection in children ages 2 months and older. A middle ear infection is also known as acute otitis media. (In this context, “acute” means the infection is short-term.)

Symptoms of acute otitis media may include pain or pressure in the ear. Children may also have a fever, pull on their ear, or cry more than usual.

Specifically, Bactrim and Bactrim DS are approved to treat middle ear infections caused by certain types of bacteria. These include Streptococcus pneumoniae or Haemophilus influenzae.

Note that Bactrim and Bactrim DS are not approved to help prevent ear infections or for long-term treatment of ear infections.

Bactrim for chronic bronchitis

Bactrim and Bactrim DS are FDA-approved to treat acute (sudden or short-term) worsening of chronic bronchitis in adults. This is also known as an acute exacerbation of chronic bronchitis.

Symptoms may include cough, trouble breathing, or wheezing that are more severe or frequent than usual.

Specifically, Bactrim and Bactrim DS are approved for this condition when it’s caused by certain types of bacteria. These include Streptococcus pneumoniae or Haemophilus influenzae.

Bactrim for shigellosis

Bactrim and Bactrim DS are FDA-approved to treat shigellosis in adults and children ages 2 months and older.

Shigellosis is a type of dysentery infection caused by certain types of bacteria. These include Shigella flexneri and Shigella sonnei. Symptoms may include:

  • diarrhea, which may contain blood
  • fever
  • abdominal pain

Bactrim for pneumocystis pneumonia

Bactrim and Bactrim DS are FDA-approved to treat and prevent pneumocystis pneumonia in adults and children ages 2 months and older.

Pneumocystis pneumonia is a lung infection caused by the fungus Pneumocystis jirovecii. This infection is more likely to affect people who have a weakened immune system, such as those with HIV or AIDS.

Symptoms commonly include trouble breathing, chest pain, and fever.

Bactrim for traveler’s diarrhea

Bactrim and Bactrim DS are FDA-approved to treat traveler’s diarrhea in adults.

Traveler’s diarrhea is defined as having at least three episodes of diarrhea (loose, watery stools) in a 24-hour period during travel abroad. It’s often caused by consuming contaminated food or water. Or it may be caused by consuming water that contains different bacteria than what your body is used to at home.

Specifically, Bactrim and Bactrim DS are used for traveler’s diarrhea caused by Escherichia coli (also known as E. coli).

Bactrim and children

Bactrim and Bactrim DS are FDA-approved for the following conditions in children* ages 2 months and older, in certain situations:

  • to treat urinary tract infection (UTI)
  • to treat middle ear infection
  • to treat a type of dysentery infection called shigellosis
  • to treat or prevent pneumocystis pneumonia

Note that doctors do not prescribe Bactrim or Bactrim DS for infants younger than 2 months old.

* Doctors may prescribe an oral suspension (liquid) form of this medication for adults and children who cannot swallow oral tablets. However, the brand-name Bactrim suspension is no longer available, but generic versions are available. This article focuses on Bactrim and Bactrim DS, which only come as oral tablets. For more information about generic sulfamethoxazole/trimethoprim oral suspension, talk with your doctor or pharmacist.

Here are answers to some frequently asked questions about Bactrim and Bactrim DS.

Can Bactrim be used for cellulitis, strep throat, a tooth infection, or a STD?

Possibly. Doctors prescribe Bactrim or Bactrim DS to treat various bacterial infections. However, these medications are not specifically FDA-approved for treating cellulitis, strep throat, tooth infections, or sexually transmitted infections.

Doctors may prescribe Bactrim or Bactrim DS off-label for these uses. With off-label use, doctors prescribe a drug for a purpose other than what the FDA has specifically approved it for.

Talk with your doctor or pharmacist if you have questions about the uses of Bactrim or Bactrim DS.

Are there certain foods to avoid while taking Bactrim?

No. There are no known interactions between food and Bactrim oral tablets.

You can take Bactrim or Bactrim DS with or without food. Be sure to take each dose with plenty of water as this helps to prevent kidney stones.

Talk with your doctor or pharmacist if you have questions about consuming specific foods with medications.

Is Bactrim safe for older adults?

Possibly, but older adults (people ages 65 years and older) should use Bactrim and Bactrim DS with caution. This is because older adults are more likely to experience serious side effects of the drug. Examples include severe skin reactions, blood disorders, and kidney problems.

Compared to younger adults, older adults are more likely to have certain conditions or take medications that further increase the risk or severity of the drug’s side effects.

Also, the trimethoprim component (one of the active ingredients in Bactrim and Bactrim DS) may lead to hyperkalemia (high levels of potassium in the blood) in older people.

If doctors prescribe Bactrim for an older adult, they may prescribe a lower dosage. They may also monitor them closely for side effects.

Talk with your doctor or pharmacist if you have questions about the safety of Bactrim or Bactrim DS.

The dosage your doctor prescribes will depend on several factors. These include:

  • whether your doctor prescribes Bactrim or Bactrim DS
  • the type and severity of your infection
  • your age
  • body weight (for certain uses)
  • body surface area (for a specific use in children)
  • other medical conditions you may have, such as kidney problems

The following information describes dosages that are commonly used or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Bactrim and Bactrim DS are available as oral tablets. The strengths are described in milligrams (mg) as follows:

  • Bactrim: 400 mg sulfamethoxazole/80 mg trimethoprim
  • Bactrim DS (“double strength”): 800 mg sulfamethoxazole/160 mg trimethoprim

Dosage for urinary tract infections (UTI)

For treating a UTI in adults, the typical dosage is either:

  • two tablets of Bactrim (400 mg/80 mg) taken every 12 hours for 10–14 days
  • one tablet of Bactrim DS (800 mg/160 mg) taken every 12 hours for 10–14 days

Dosage for chronic bronchitis

For treating an acute flare of chronic bronchitis in adults, the typical dosage is either:

  • two tablets of Bactrim (400 mg/80 mg) taken every 12 hours for 14 days
  • one tablet of Bactrim DS (800 mg/160 mg) taken every 12 hours for 14 days

Dosage for shigellosis

For treating shigellosis in adults, the typical dosage is either:

  • two tablets of Bactrim (400 mg/80 mg) taken every 12 hours for 5 days
  • one tablet of Bactrim DS (800 mg/160 mg) taken every 12 hours for 5 days

Dosage for pneumocystis pneumonia

For treating pneumocystis pneumonia in adults, your dose will depend on your body weight in kilograms (kg).* The recommended dose range per day is 75–100 mg/kg of sulfamethoxazole and 15–20 mg/kg of trimethoprim, given in divided doses. Your doctor will tell you how many tablets to take for each dose. You’ll take this dose every 6 hours for 14–21 days.

Example: If someone weighs 64 kg (about 141 lb), their doctor may prescribe four tablets of Bactrim (400 mg/80 mg) taken every 6 hours for 14–21 days. Alternatively, their doctor may prescribe two tablets of Bactrim DS (800 mg/160 mg) taken every 6 hours for 14–21 days.

To prevent pneumocystis pneumonia in adults, the typical dosage is one tablet of Bactrim DS (800 mg/160 mg) taken once daily.

* One kg equals about 2.2 pounds (lb).

Dosage for traveler’s diarrhea

For treating traveler’s diarrhea in adults, the typical dosage is either:

  • two tablets of Bactrim (400 mg/80 mg) taken every 12 hours for 5 days
  • one tablet of Bactrim DS (800 mg/160 mg) taken every 12 hours for 5 days

Children’s dosage

The following information describes dosages that are commonly used or recommended. However, be sure your child takes the dosage their doctor prescribes for them. Your doctor will determine the best dosage to fit your childs needs.

Children’s dosage for UTI or middle ear infection

For treating UTI or middle ear infection in children* ages 2 months and older, the dose of Bactrim depends on your child’s body weight in kg. The recommended dose per day is 40 mg/kg of sulfamethoxazole and 8 mg/kg of trimethoprim, given in divided doses every 12 hours for 10 days. (Sulfamethoxazole and trimethoprim are the two active ingredients in Bactrim and Bactrim DS.)

For example, if your child weighs 20 kg (about 44 lb), their doctor may prescribe 1 tablet of Bactrim (400 mg/80 mg) taken every 12 hours for 10 days.

Children’s dosage for shigellosis

For treating shigellosis in children* ages 2 months and older, the dose of Bactrim depends on your child’s body weight in kg. The recommended dose per day is 40 mg/kg of sulfamethoxazole and 8 mg/kg of trimethoprim, given in divided doses every 12 hours for 5 days.

For example, if your child weighs 20 kg (about 44 lb), their doctor may prescribe one tablet of Bactrim (400 mg/80 mg) taken every 12 hours for 5 days.

Children’s dosage for pneumocystis

For treating pneumocystis pneumonia in children* ages 2 months and older, the dose of Bactrim depends on your child’s body weight in kg. The recommended dose range per day is 75–100 mg/kg of sulfamethoxazole and 15–20 mg/kg of trimethoprim, given in divided doses every 6 hours for 14–21 days.

For example, if your child weighs 32 kg (about 70 lb), their doctor may prescribe two tablets of Bactrim (400 mg/80 mg) taken every 6 hours for 14–21 days. Alternatively, their doctor may prescribe one tablet of Bactrim DS (800 mg/160 mg) taken every 6 hours for 14–21 days.

Children’s dosage for preventing pneumocystis

For preventing pneumocystis pneumonia in children* ages 2 months and older, the dose of Bactrim depends on your child’s body surface area (BSA) in squared meters (m2). (Your doctor will calculate your child’s BSA using their height and weight.) The recommended dose per day is 750 mg/m2 of sulfamethoxazole and 150 mg/m2 of trimethoprim, given in divided doses twice a day on three consecutive days each week.

For example, if your child has a BSA of 1.06 m2, their doctor may prescribe one tablet of Bactrim (400 mg/80 mg) taken twice a day on Mondays, Tuesdays, and Wednesdays. On the other days of the week, the child will not take any doses of Bactrim.

Talk with your doctor or pharmacist if you have questions about your child’s dosage of Bactrim or Bactrim DS.

* Doctors may prescribe an oral suspension (liquid) form of this medication for adults and children who cannot swallow oral tablets. However, the brand-name Bactrim suspension is no longer available, but generic versions are available. This article focuses on Bactrim and Bactrim DS, which only come as oral tablets. For more information about generic sulfamethoxazole/trimethoprim oral suspension, talk with your doctor or pharmacist.

About taking Bactrim

Below you’ll find information about key dosage issues.

  • When to take: Bactrim and Bactrim DS are typically taken once every 12 hours. For example, you may take one dose at 7:00 a.m. and one dose at 7:00 p.m. Taking the medication every 12 hours (or as prescribed by your doctor) helps the drug work effectively.
  • If you miss a dose: If you miss a dose of Bactrim or Bactrim DS, take it as soon as you remember. However, if it’s nearly time for the next dose, just skip the missed dose. Continue taking your regular dose at the next scheduled time. If you’re not sure what to do after missing a dose, talk with your doctor or pharmacist.
  • Taking medication with food:You may take Bactrim or Bactrim DS with or without food. Be sure to take each dose with plenty of water as this helps to prevent kidney stones.
  • Crushing, splitting, or chewing Bactrim or Bactrim DS: Bactrim and Bactrim DS tablets are scored. This means the tablets have a perforation line down the center that allows you to split them in half safely. However, the manufacturer of Bactrim and Bactrim DS does not offer guidance on the safety of crushing or chewing this medication. If you have trouble swallowing these tablets, talk with your doctor or pharmacist for advice.
  • Length of use: Bactrim and Bactrim DS are typically used as a short-term treatment. Some people may need to take it long-term to treat or help prevent a specific type of infection. Talk with your doctor about how long you’ll take this medication.
Finishing your antibiotics

Even if you feel better after a few days of treatment, you should never stop taking an antibiotic without first talking with your doctor. Stopping a course of antibiotics before it’s finished can cause the infection to return, perhaps even stronger than before. If it returns, it could be resistant to the antibiotic you were taking. That means the drug would no longer work to treat your infection.

If you have side effects from your antibiotic or other concerns, talk with your doctor. They can help manage the side effects or answer any questions you may have.

Overdose

Using more than the recommended dosage of Bactrim or Bactrim DS can lead to serious side effects. Do not use more Bactrim or Bactrim DS than your doctor recommends.

Overdose symptoms

Signs and symptoms of an overdose can include:

  • nausea and vomiting
  • dizziness
  • headache
  • lack of appetite
  • drowsiness
  • fever
  • bloody urine
  • jaundice
  • confusion
  • loss of consciousness
  • low levels of blood cells, such as white blood cells, red blood cells, and platelets

What to do in case of overdose

If you think you’ve taken too much of this drug, call your doctor. You can also call America’s Poison Centers at 800-222-1222 or use its online tool. However, if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

Bactrim and Bactrim DS can interact with several other medications.

Before taking Bactrim or Bactrim DS, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

Interactions with medications

Below is a list of medications and lab tests that can interact with Bactrim and Bactrim DS. This is not a complete list of interactions with Bactrim and Bactrim DS. If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Medications that can interact with Bactrim• diuretics, such as hydrochlorothiazide (Microzide)
• warfarin (Jantoven)
• phenytoin (Dilantin)
• methotrexate (Trexall)
• cyclosporine (Gengraf, Neoral)
• digoxin (Lanoxin)
• indomethacin (Indocin)
• pyrimethamine (Daraprim)
• tricyclic antidepressants, such as amitriptyline or nortriptyline (Pamelor)
• certain diabetes medications, such as glipizide (Glucotrol XL) or pioglitazone (Actos)
• amantadine
• angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril (Zestril) or ramipril (Altace)
• zidovudine (Retrovir)
• dofetilide (Tikosyn)
• procainamide
• leucovorin
Lab tests that can interact with Bactrim• a certain lab test used to measure the blood level of a drug called methotrexate
• a certain lab test used to measure creatinine

Alcohol interaction

Alcohol is not known to interact with Bactrim or Bactrim DS. If you have questions about how much alcohol is safe to drink while taking this medication, talk with your doctor or pharmacist.

If you can become pregnant, consider the following information about pregnancy and breastfeeding.

Bactrim and pregnancy

Bactrim and Bactrim DS should not be taken during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this medication. Your doctor may suggest birth control options to use during treatment with Bactrim or Bactrim DS.

Bactrim and birth control

Bactrim and Bactrim DS are not safe to take during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re using Bactrim or Bactrim DS.

Bactrim and breastfeeding

Doctors may not recommend Bactrim or Bactrim DS while breastfeeding, especially if your child is younger than 2 months old or has certain medical conditions.

If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication. Depending on the age and health of your child, your doctor may recommend other feeding methods during treatment with Bactrim or Bactrim DS.

Other drugs are available that can treat your condition. Some may be a better fit for you than others. If you’re interested in finding an alternative to Bactrim or Bactrim DS, talk with your doctor. They can tell you about other medications that may work well for you.

The following drugs are similar to Bactrim and Bactrim DS:

  • sulfamethoxazole/trimethoprim (Septra, Septra DS)
  • sulfamethoxazole/trimethoprim (Sulfatrim Pediatric)

As with all medications, the cost of Bactrim and Bactrim DS can vary. The actual price you’ll pay depends on your insurance plan, your location, and the pharmacy you use.

Drug coupons: You can visit Optum Perks for price estimates of Bactrim and Bactrim DS. These estimates are based on the use of Optum Perks coupons. Note: Optum Perks coupons cannot be used with any insurance copays or benefits.

Financial and insurance assistance:If you need financial support to pay for Bactrim or Bactrim DS, or if you need help understanding your insurance coverage, help is available.

To learn more about saving money on prescriptions, check out this article.

Generic version: Bactrim and Bactrim DS are available in a generic form called sulfamethoxazole/trimethoprim. A generic drug is an exact copy of the active ingredients in a brand-name medication. The generic is considered to be as safe and effective as the original drug. And generics tend to cost less than brand-name drugs. To find out how the cost of sulfamethoxazole/trimethoprim compares to the cost of Bactrim or Bactrim DS, talk with your doctor or pharmacist.

To learn more about saving money on prescriptions, check out this article.

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This drug comes with several precautions.

Before taking Bactrim or Bactrim DS, discuss your health history with your doctor. This drug may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

Note: For more information about the potential negative effects of Bactrim or Bactrim DS, see the “Bactrim side effects” section above.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.