Septra Side Effects Center

Last updated on RxList: 5/25/2022
Septra Side Effects Center

What Is Septra?

Septra (trimethoprim and sulfamethoxazole) is a combination of two antibiotics used to treat ear infections, urinary tract infections, bronchitis, traveler's diarrhea, methicillin-resistant Staphylococcus aureus (MRSA) and Pneumocystis carinii pneumonia. Septra is available in generic form.

What Are Side Effects of Septra?

Common side effects of Septra include:

Tell your doctor if you have serious side effects of Septra including:

  • muscle weakness,
  • mental/mood changes,
  • blood in the urine,
  • changes in the amount of urine,
  • extreme drowsiness, or
  • signs of low blood sugar (such as nervousness, shakiness, sweating, hunger).

Dosage for Septra

The dose of Septra varies depending on the condition being treated.

What Drugs, Substances, or Supplements Interact with Septra?

Septra may interact with seizure medications, diuretics (water pills), blood thinners, methotrexate, or ACE inhibitors. Tell your doctor all medications you use.

Septra During Pregnancy and Breastfeeding

During pregnancy, Septra should be used only when prescribed. It should not be used near the expected delivery date because of possible harm to the fetus. This drug passes into breast milk. While there have been no reports of harm to healthy infants, this drug may have undesirable effects on infants who are ill or premature or have certain disorders (jaundice, high blood levels of bilirubin, G6PD deficiency). Breastfeeding is not recommended for infants with these conditions. Consult your doctor before breastfeeding.

Additional Information

Our Septra (trimethoprim and sulfamethoxazole) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Septra Consumer Information

Get emergency medical help if you have signs of an allergic reaction (hives, cough, chest pain, shortness of breath, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, joint pain, muscle aches, severe weakness, pale skin, unusual bruising, or yellowing of your skin or eyes.

Call your doctor at once if you have:

  • severe stomach pain, diarrhea that is watery or bloody (even if it occurs months after your last dose);
  • any skin rash, no matter how mild;
  • yellowing of your skin or eyes;
  • a seizure;
  • new or unusual joint pain;
  • increased or decreased urination;
  • swelling, bruising, or irritation around the IV needle;
  • increased thirst, dry mouth, fruity breath odor;
  • new or worsening cough, fever, trouble breathing;
  • high blood potassium--nausea, weakness, tingly feeling, chest pain, irregular heartbeats, loss of movement;
  • low blood sodium--headache, confusion, problems with thinking or memory, weakness, feeling unsteady; or
  • low blood cell counts--fever, chills, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath.

Common side effects may include:

  • nausea, vomiting, loss of appetite; or
  • skin rash.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Septra Professional Information


The following adverse reactions associated with the use of SEPTRA or trimethoprim-sulfamethoxazole were identified in clinical studies, postmarketing or published reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

The most common adverse effects are gastrointestinal disturbances (nausea, vomiting, anorexia) and allergic skin reactions (such as rash and urticaria). Fatalities associated with the administration of sulfonamides have occurred due to severe cutaneous adverse reactions (SCARs), including Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms(DRESS), fulminant hepatic necrosis, agranulocytosis, aplastic anemia, other blood dyscrasias, acute and delayed lung injury, anaphylaxis, and circulatory shock (see WARNINGS).


Agranulocytosis, aplastic anemia, thrombocytopenia, leukopenia, neutropenia, hemolytic anemia, megaloblastic anemia, hypoprothrombinemia, methemoglobinemia, eosinophilia, thrombotic thrombocytopenic purpura, idiopathic thrombocytopenic purpura.


Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS, acute generalized exanthematous pustulosis (AGEP), acute febrile neutrophilic dermatosis (AFND), anaphylaxis, allergic myocarditis, erythema multiforme, exfoliative dermatitis, angioedema, drug fever, chills, Henoch-Schonlein purpura, serum sickness-like syndrome, generalized allergic reactions, generalized skin eruptions, photosensitivity, conjunctival and scleral injection, pruritus, urticaria, and rash. In addition, periarteritis nodosa and systemic lupuse rythematosus have been reported.


Hepatitis, including cholestatic jaundice and hepatic necrosis, elevation of serum transaminases and bilirubin, pseudomembranous enterocolitis, pancreatitis, stomatitis, glossitis, nausea, emesis, abdominal pain, diarrhea, anorexia.


Renal failure, interstitial nephritis, BUN and serum creatinine elevation, renal insufficiency, anuria, crystalluria, and nephrotoxicity in association with cyclosporine.


Hyperkalemia, hyponatremia (see PRECAUTIONS: Electrolyte Abnormalities).


Asepticmeningitis, convulsions, peripheralneuritis, ataxia, vertigo, tinnitus, headache.


Hallucinations, depression, apathy, nervousness.


The sulfonamides bear certain chemical similarities to some goitrogens, diuretics (acetazolamide and the thiazides), and oral hypoglycemic agents. Cross-sensitivity may exist with these agents. Diuresis and hypoglycemia have occurred rarely in patients receiving sulfonamides.


Arthralgia and myalgia. Cases of rhabdomyolysis have been reported with SEPTRA, mainly in AIDS patients.

Respiratory System

Cough, shortness of breath, pulmonary infiltrates, acute eosinophilic pneumonia, acute and delayed lung injury, interstitial lung disease, and acute respiratory failure (see WARNINGS).

Cardiovascular System

QT prolongation resulting in ventricular tachycardia and torsade de pointes, circulatory shock.


Weakness, fatigue, insomnia.

Read the entire FDA prescribing information for Septra (Trimethoprim and Sulfamethoxazole)

© Septra Patient Information is supplied by Cerner Multum, Inc. and Septra Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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