Antibiotics Home > Septra Warnings and Precautions

If you have anemia, asthma, or porphyria, let your healthcare provider know before taking Septra. Warnings and precautions for the drug should also be discussed with your healthcare provider, as it is important to know what side effects may occur (such as fever, hypoglycemia, and watery or bloody diarrhea). You should not take Septra if you have severe kidney problems or significant liver disease.

What Should I Tell My Healthcare Provider Before Taking Septra?

You should talk with your healthcare provider prior to taking Septra® (sulfamethoxazole/trimethoprim) if you have:
  • HIV or AIDS
  • Kidney disease, such as kidney failure (renal failure)
  • Liver disease, such as liver failure, cirrhosis, or hepatitis
  • Anemia
  • Asthma
  • Glucose-6-phosphate dehydrogenase deficiency
  • A folic acid deficiency
  • Phenylketonuria (PKU)
  • A thyroid disorder
  • Porphyria
  • Any other allergies, including allergies to food, dyes, or preservatives.
Also, let your healthcare provider know if you are:
  • Pregnant or thinking of becoming pregnant
  • Breastfeeding.
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.

Specific Precautions and Warnings for Septra

Some warnings and precautions to be aware of with Septra include the following:
  • Septra contains a sulfonamide (a "sulfa" drug). Do not take Septra if you have a sulfa allergy.
  • Rarely, Septra has caused deaths due to various problems, although it is generally a relatively safe antibiotic for most people.
  • Let your healthcare provider know if you develop an unexplained sore throat, fever, joint pain, pale skin, bruising, yellow skin (jaundice), coughing, or shortness of breath while taking Septra. These may be signs of serious reactions to Septra.
  • Stop taking Septra and contact your healthcare provider immediately if you develop a skin rash while taking it. While it may just be a simple rash, it could turn out to be a life-threatening reaction, such as Stevens-Johnson syndrome or toxic epidermal necrolysis.
  • Let your healthcare provider know if you experience bloody or watery diarrhea. While diarrhea is a common side effect of antibiotics, bloody or watery diarrhea may be a sign of a serious reaction to Septra that can occur when certain bacteria (Clostridium difficile) overgrow in the colon. This severe reaction can occur long after you stop taking Septra and can be life-threatening.
  • Check with your healthcare provider before taking Septra if you have glucose-6-phosphate dehydrogenase deficiency or severe asthma, as serious Septra side effects could occur.
  • Septra can cause electrolyte problems, such as high potassium or low sodium levels in the blood. If you already have electrolyte problems or if you have kidney problems, your electrolytes should be monitored using blood tests while taking this medication. 
  • Septra should not be used to treat infections caused by β-hemolytic streptococcal bacteria, as it is not effective for completely getting rid of this type of bacteria (which might increase the risk of developing rheumatic fever due to the infection).
  • Overuse of antibiotics (including Septra) increases the risk for developing antibiotic-resistant bacteria. Your healthcare provider should prescribe antibiotics only when necessary (and only to treat bacterial infections). Antibiotics are not effective for treating viral infections, such as the common cold or the flu.
  • Make sure your healthcare provider knows if you have kidney or liver disease, as you may need a lower Septra dosage (or Septra may not be recommended, in severe cases).
  • There have been reports of low blood sugar (hypoglycemia) possibly due to Septra. While most common in people with diabetes, it has also been reported in non-diabetic individuals.
  • Septra may worsen certain thyroid disorders (especially hypothyroidism) or porphyria. If you have either of these problems, check with your healthcare provider before taking Septra.
  • Although Septra is approved to treat and prevent Pneumocystis carinii pneumonia in people with HIV or AIDS, it should be noted that people with HIV or AIDS have a higher risk of Septra side effects. Your healthcare provider should carefully monitor you for Septra side effects.
  • It is very important to take Septra exactly as prescribed. Skipping doses or stopping Septra too early (even if you feel better) can lead to bacterial resistance to Septra.
  • Septra can interact with many other medications (see Septra Drug Interactions).
  • Septra is considered a pregnancy Category D medication. This means that it is probably not safe for use during pregnancy, although the full risks are not known. Talk to your healthcare provider about the risks and benefits of using this drug when pregnant (see Septra and Pregnancy for more information).
  • Septra passes through breast milk. Therefore, if you are breastfeeding or plan to start, be sure to talk with your healthcare provider about using Septra (see Septra and Breastfeeding for more information).
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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