Side Effects for Sulfamethoxazole-Tmp

Sulfamethoxazole-Tmp, sold under the brands names of Bactrim or Septra, is an antibiotic medication used to treat such bacterial infections as bronchitis, traveler's diarrhea and pneumocystis carinii pneumonia (a type of lung infection usually found in patients with AIDS). Sulfamethoxazole-Tmp is available as a tablet or liquid syrup and should be taken as your doctor prescribes. If you are taking sulfamethoxazole-tmp, you should be aware of its side effects.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

Common Side Effects

According to, sulfamethoxazole-tmp commonly leads to allergic or gastrointestinal (stomach or intestinal) side effects 2. Symptoms of an allergic reaction include skin sensitivity, itchiness, anaphylaxis (trouble breathing and swelling of your throat or face), scleral injection (red eyes) and urticaria (hives). Sulfamethoxazole-Tmp can harm your digestive tract and lead to pancreatitis (inflammation of your pancreas), hepatitis (liver disorder), nausea, vomiting and diarrhea. Users may also experience stomach pain, glossitis (red tongue) and anorexia (an eating disorder).

Severe Side Effects

Sulfamethoxazole-Tmp can also cause serious side effects that, if left untreated, can do serious damage. According to, these severe side effects include:

  • skin blistering
  • fever
  • sore throat
  • shortness of breath
  • cough
  • bradycardia (slow heartbeat)
  • chills 1

You may also experience nausea, body aches, muscle pain and weakness. Seek emergency medical help if you have these symptoms.

Other Side Effects states that sulfamethoxazole-tmp can further affect your body in harmful ways 2. You may have convulsions, hallucinations (hearing or seeing things that aren't present), feel fatigued and have trouble sleeping. Sulfamethoxazole-Tmp can also affect your blood cell count and lead to anemia (low red blood cell levels) or hyperkalemia (high potassium levels).

Signs of Overdose

If you take more sulfamethoxazole-tmp than your doctor prescribes, symptoms of an overdose can result. states that these symptoms include:

  • nausea
  • vomiting
  • dizziness
  • drowsiness
  • stomach pain
  • urine in your blood 1

You may also have confusion, loss of appetite, headaches, stomach pain and fainting spells.


According to, sulfamethoxazole-tmp can lead to serious medical conditions that may result in a fatality. However, this is a rare occurrence. For example, you may develop Steven's Johnson syndrome (skin disease characterized by swelling and a red or purple rash), toxic epidermal necrolysis (skin disease characterized by itchiness and skin lesions), hepatic necrosis (liver death) and blood disorders. You may also develop a bacterial diarrheal infection cause by Clostridium Difficile. You should promptly be treated with antibiotics such as Flagyl to prevent electrolyte (minerals in your blood) imbalance and other serious symptoms.