Medically reviewed by Jessica Swirble, PharmD
Last updated on 5/11/2024

Drug Information | Side Effects | Use & Dosage| Request a Prescription

Sulfamethoxazole-trimethoprim, commonly known as Bactrim, is available in various strengths, including:

• Oral tablets (400 mg sulfamethoxazole/80 mg trimethoprim, 800 mg sulfamethoxazole/160 mg trimethoprim)
  
• Oral suspension (200 mg sulfamethoxazole/40 mg trimethoprim per 5 mL)
  
  

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:

• One double-strength tablet (800 mg sulfamethoxazole/160 mg trimethoprim) taken orally twice daily
  
• Two single-strength tablets (400 mg sulfamethoxazole/80 mg trimethoprim) taken orally twice daily
  
  

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.