Medically reviewed by Jessica Swirble, PharmD
Last updated on March 31, 2025
Drug Information | Side Effects | Use & Dosage | Request an Online Prescription
Sulfamethoxazole-trimethoprim is a combination antibiotic medication. It is commonly prescribed to treat bacterial infections such as urinary tract infections, respiratory tract infections, traveler's diarrhea, and certain types of pneumonia.
Sulfamethoxazole-trimethoprim is used to treat conditions such as:
It may also be prescribed for other bacterial infections as determined by your healthcare provider.
Sulfamethoxazole-trimethoprim works by inhibiting the production of folic acid in bacteria, which is essential for their growth and survival. By blocking this process, sulfamethoxazole-trimethoprim effectively kills or stops the growth of bacteria causing the infection.
Sulfamethoxazole-trimethoprim is typically taken orally, with a full glass of water, as directed by your healthcare provider.
You can take sulfamethoxazole-trimethoprim with or without food. Taking it with food may prevent stomach upset and irritation.
It is important to follow the prescribed dosage and schedule. Do not skip doses or stop taking sulfamethoxazole-trimethoprim before completing the full course, even if you feel better.
Consult your healthcare provider for specific instructions on how to take sulfamethoxazole-trimethoprim properly.
The time it takes to experience improvement in symptoms while taking sulfamethoxazole-trimethoprim can vary depending on the type and severity of the infection. Some people may start feeling better within a few days, while others may require the full course of treatment to see significant results. It's crucial to complete the prescribed course of sulfamethoxazole-trimethoprim as directed.
While sulfamethoxazole-trimethoprim is primarily used for bacterial infections, healthcare providers may sometimes prescribe it off-label for other conditions, such as:
Discuss any alternative uses of sulfamethoxazole-trimethoprim with your healthcare provider.
Sulfamethoxazole-trimethoprim is available in its generic form (sulfamethoxazole-trimethoprim) in the following dosage forms:
The brand name sulfamethoxazole-trimethoprim has been discontinued. You can only get this medication in its generic form.
Sulfamethoxazole-trimethoprim is a prescription medication. You will need a valid prescription from a licensed healthcare provider to obtain this drug.
The use of sulfamethoxazole-trimethoprim has been shown to cause side effects in some patients.
Common mild side effects of sulfamethoxazole-trimethoprim use include:
More severe side effects include:
Seek medical attention immediately if you experience any severe symptoms while taking sulfamethoxazole-trimethoprim. If you experience mild side effects that become severe or do not go away after a few days, speak to a healthcare provider right away.
Tell your healthcare provider about any existing medical conditions, allergies, or other medications you are taking before starting treatment with sulfamethoxazole-trimethoprim. This includes prescription drugs, over-the-counter medications, and dietary supplements, as they may interact with this drug.
Tell your provider if you are taking these medications or supplements:
You should also mention medical conditions such as:
If you are pregnant, planning to become pregnant, or breastfeeding, consult your healthcare provider before using sulfamethoxazole-trimethoprim to assess potential risks and benefits.
You can follow your regular diet while taking sulfamethoxazole-trimethoprim. Talk to your healthcare provider about the use of this drug with food, beverages, alcohol, and tobacco.
Your healthcare provider will provide specific instructions regarding the use of sulfamethoxazole-trimethoprim with food, beverages, and other medications. It's essential to follow their guidance to ensure the effectiveness of the treatment and minimize the risk of side effects.
The symptoms of a sulfamethoxazole-trimethoprim overdose include:
If you experience any of these symptoms, call the poison control helpline at 1-800-222-1222. If an individual has collapsed, is having seizures, or is unresponsive, call 9-1-1 immediately.
Sulfamethoxazole-trimethoprim, commonly known as Bactrim, is available in various strengths, including:
The typical starting dose of sulfamethoxazole-trimethoprim for bacterial infections can vary depending on factors such as the type and severity of the infection, your age, kidney function, and other medical conditions. It's crucial to follow your healthcare provider's instructions regarding dosage and administration carefully.
For most adults and children 12 years and older with uncomplicated infections, the typical starting dose of sulfamethoxazole-trimethoprim may be:
For children younger than 12 years old or for specific infections, the dose may be adjusted based on weight and the severity of the condition. Oral suspension is often used for pediatric dosing.
Take sulfamethoxazole-trimethoprim with a full glass of water. It can be taken with or without food. Taking sulfamethoxazole-trimethoprim with food may help decrease stomach upset.
Your healthcare provider will determine the duration of treatment based on the type of infection being treated and your response to the medication. It's important not to skip doses and to complete the full course of treatment as prescribed, even if you start feeling better.
If you have any questions about your dosage or how to take sulfamethoxazole-trimethoprim, contact your healthcare provider or pharmacist. If you want to talk to a provider right away, consider booking an online doctor appointment on Sesame to discuss your concerns.
If you miss a dose, take it as soon as you remember it. If it's almost time for another dose of sulfamethoxazole-trimethoprim, skip the missed dose and take your next dose as scheduled. Do not take or apply a double dose of sulfamethoxazole-trimethoprim.
Do not discontinue or alter your sulfamethoxazole-trimethoprim dosage without consulting with your healthcare provider. Follow your healthcare provider's instructions regarding dosing and other recommendations for taking sulfamethoxazole-trimethoprim.
Store sulfamethoxazole-trimethoprim as directed by your healthcare provider or pharmacist. Proper storage is essential to maintain the medication's effectiveness. Sulfamethoxazole-trimethoprim should be stored at room temperature, away from excessive heat, light, and moisture.
Keep the medication out of the reach of children and ensure that the container is tightly closed.