Bactrim DS Dosages: Your GoodRx Guide

Bactrim DS is a popular antibiotic that treats bacterial infections like urinary tract infections (UTIs), ear infections, and certain types of pneumonia. It’s made up of two medications, sulfamethoxazole and trimethoprim, which work together to kill bacteria and resolve infections in the body. It belongs to a group of medications called sulfa antibiotics.

You can find this combination antibiotic on pharmacy shelves as branded products such as Bactrim DS and Sulfatrim Pediatric. It also comes as Septra and Septra DS. What’s more, it’s available as a lower-cost generic as an oral tablet and liquid suspension. Each tablet of Bactrim DS — which stands for “double strength” — contains 800 mg of sulfamethoxazole and 160 mg of trimethoprim. You may have also heard of Bactrim SS, or “single strength,” which contains 400 mg of sulfamethoxazole and 80 mg of trimethoprim.

Here, we’ll discuss common Bactrim DS dosages for adults and children as well as some other tips to keep in mind.

What’s the typical Bactrim DS dosage for adults?

In most cases, adults will take Bactrim DS for 5 to 14 days at a time. This can be longer or shorter depending on the type of infection that’s being treated and how severe your symptoms are.

In some cases, Bactrim DS can also be prescribed long-term to prevent complications in people who are at a higher risk for certain types of infections. This can be useful for people with weakened immune systems, such as those living with HIV or who are receiving high doses of chemotherapy. Prevention dosages are different from dosages used to treat an active infection.

In order to most effectively resolve an infection, it’s important to take all antibiotics exactly as they are prescribed. Bactrim DS is no different. You should take your entire course of Bactrim DS even if your symptoms start to improve and you feel better. This helps ensure the infection is cleared from your body and lowers your risk of having the infection come back.

What’s the typical Bactrim DS dosage for children?

Bactrim DS dosages for children ages 2 months or older are based on body weight. Your child’s healthcare provider will calculate their dosage for them based on their body weight in kilograms (kg).

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Like adults, Bactrim DS courses in children typically last 5 to 14 days depending on the type of infection being treated and how severe their symptoms are. However, you should give your child all of their prescribed doses even if they start to feel better.

If your child is younger than 2 months old, they generally shouldn’t receive Bactrim DS. Speak with your healthcare provider about an alternative antibiotic for your child’s infection.

Are there any Bactrim DS dosage adjustments for medical conditions?

Yes, there are recommended dosage adjustments for people with substantial kidney problems. This is because Bactrim DS leaves your body through your kidneys. If your kidneys aren’t working properly, Bactrim DS could build up in your body. This can lead to unwanted side effects.

Dosage for people with kidney problems

If you have mild to moderate kidney problems, you most likely won’t need to adjust your dosage of Bactrim DS.

But if you have severe kidney problems, you’ll need to take a lower dosage. Your dose will likely be based on your “creatinine clearance” (CrCl). This is a lab test that helps your healthcare provider figure out how efficient your kidneys are working, and it determines the most appropriate Bactrim DS dosage based on your kidney health.

What happens if you miss a dose of Bactrim DS?

Missing a dose of Bactrim DS may make your treatment less effective. If you miss a dose of Bactrim DS, you should take it as soon as you remember. But if you remember within a few hours before your next scheduled dose, you can skip the missed dose altogether and wait to take the next dose at your regular scheduled time.

Do not try to catch up by taking two doses of Bactrim DS at once. Taking too many doses at once can raise your risk of side effects.

What should you do if you take too much Bactrim DS?

Bactrim DS can cause side effects like diarrhea, nausea, and vomiting at regular doses. If you take too much Bactrim DS, these side effects may become worse. Taking too much Bactrim DS can put you at risk of a Bactrim DS overdose. Signs and symptoms of a Bactrim DS overdose can include:

• Nausea and vomiting

• Dizziness

• Drowsiness

• Headache

• Confusion

• Unconsciousness

It’s less common, but taking too much Bactrim DS for a prolonged period of time can also lead to bone marrow suppression. This is when fewer blood cells are made in the bone marrow. This can lead to more severe consequences like low red blood cells (anemia), low white blood cells, and low platelets.

As a precaution, you should contact a healthcare provider right away if you think you or your child took too much Bactrim DS. They can help advise you on what to do and how to manage symptoms of Bactrim DS overdose. You could also contact Poison Control by phone at 1-800-222-1222 for guidance. However, if your symptoms feel severe, it’s better to call 911 or go to the nearest emergency room.

How to save on Bactrim DS

There are ways to save on Bactrim DS, which is available as both a brand-name and generic medication. GoodRx can help you save over 70% off the average retail price of the generic version. Generic Bactrim’s price at certain pharmacies is as low as $5.25 with a free GoodRx discount.

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Written by:

Sonja Jacobsen, PharmD, BCPS, BCOP

Sonja Jacobsen, PharmD, BCPS, BCOP,  is a clinical oncology pharmacy specialist currently practicing in Seattle. She has been practicing as a pharmacist since 2015 and is licensed to practice in Washington state and North Carolina.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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