Why is this medication prescribed?
Septra® (sulfamethoxazole/trimethoprim) is a combination of 2 antibiotics, sulfamethoxazole, a 'sulfa' antibiotic, and trimethoprim.  In CF, Septra® is used to treat lung infections caused by specific bacteria - for example Stenotrophomonas maltophilia or Burkholderia cepacia.

How does this medication work?
Septra® works by decreasing the amount of bacteria in the lungs.

What is the usual dose?
Septra® is available in tablet, liquid or injectable form. A typical CF adult dose is 2 Double Strength (DS) tablets (800mg/160mg) by mouth twice a day.

How should this medication be taken?
This medication can be taken with or without food. If you experience stomach upset you can take it with food. It is important to drink at least 1.5L (8 glasses) of fluid a day during treatment.

Finish taking all of your medication even if you start to feel better after taking a few doses. Do not stop unless your doctor tells you to stop.

Store this medicine at room temperature away from heat, moisture and direct light.

What should I do if I miss a dose?
Do not double any dose. If you forget to take a dose, take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the next scheduled dose.

What should I expect from this medication?
You may or may not experience side effects. These side effects may disappear but let your doctor know if they are severe or if they last for more than 2 days. These include nausea, vomiting, diarrhea, or loss of appetite, but tell us if you have any other side effects as well.

Contact your doctor as soon as possible if you experience rash, hives, or difficulty breathing.

Tell your doctor of any drug allergies and previous allergic reactions with drugs before using Septra®.

If you are pregnant or think you might be pregnant, talk to your doctor before starting any antibiotics.

Septra® can cause your skin to become more sensitive to sunlight. Limit the amount of time you spend in the sun until you know how this drug affects you. While in the sun, keep your body covered with clothing and use sunscreen on exposed skin.