Daraprim Side Effects

Generic Name: pyrimethamine

Note: This page contains information about the side effects of pyrimethamine. Some of the dosage forms included on this document may not apply to the brand name Daraprim.

Not all side effects for Daraprim may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to pyrimethamine: oral tablet

In addition to its needed effects, some unwanted effects may be caused by pyrimethamine (the active ingredient contained in Daraprim). In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking pyrimethamine:

Less common
  • Black, tarry stools
  • blood in urine or stools
  • cough or hoarseness
  • fever or chills
  • irritation or soreness of tongue
  • lower back or side pain
  • painful or difficult urination
  • pinpoint red spots on skin
  • unusual bleeding or bruising
  • Bleeding or crusting sores on lips
  • chest pain or discomfort
  • muscle cramps or pain
  • redness, blistering, peeling, or loosening of skin
  • skin rash
  • sores, ulcers, and/or white spots in mouth
  • sore throat
  • unusual tiredness or weakness
Frequency not known
  • Blood in urine
  • diarrhea
  • difficulty swallowing
  • dizziness
  • fainting spells
  • fast, slow, or irregular heartbeat
  • hives
  • itching
  • joint or muscle pain
  • lightheadedness
  • pale skin
  • pounding or rapid pulse
  • puffiness or swelling of the eyelids or around the eyes, face, lips or tongue
  • rapid breathing
  • red, irritated eyes
  • red skin lesions, often with a purple center
  • shortness of breath
  • swollen glands
  • tightness in chest
  • unexplained bleeding or bruising
  • wheezing
Symptoms of overdose
  • Abdominal or stomach pain
  • convulsions (seizures)
  • increased excitability
  • vomiting (severe and continuing)

Some of the side effects that can occur with pyrimethamine may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

Less common
  • Diarrhea
  • loss of appetite
  • nausea
  • vomiting

For Healthcare Professionals

Applies to pyrimethamine: compounding powder, oral tablet


Gastrointestinal side effects have included nausea, vomiting, diarrhea, glossitis, and atrophic glossitis, particularly with high doses. Gastrointestinal intolerance may be minimized by administering pyrimethamine (the active ingredient contained in Daraprim) with food.


Hypersensitivity reactions have been reported when pyrimethamine (the active ingredient contained in Daraprim) is administered with a sulfonamide. These reactions may be severe and include erythema multiforme, Stevens-Johnson Syndrome, toxic epidermal necrolysis, Lyell's syndrome, hepatitis, anaphylaxis, and pulmonary reactions. Fatal reactions have been estimated to occur in one of 11,000 to 25,000 patients treated. Hypersensitivity reactions have also been reported with pyrimethamine/clindamycin combinations and are usually limited to maculopapular rashes.


Hematologic side effects have occurred, especially when large doses of pyrimethamine (the active ingredient contained in Daraprim) are administered. Thrombocytopenia, megaloblastic anemia, leukopenia, pancytopenia, agranulocytosis, and fatalities have been reported.

Nervous system

Nervous system toxicity is problematic with higher dosages of pyrimethamine (the active ingredient contained in Daraprim) Ataxia, tremors, and seizures may occur.


Respiratory side effects have rarely included pulmonary eosinophilia.


Cardiovascular side effects have included arrhythmias, particularly with high doses.


Metabolic side effects have included hyperphenylalaninemia, particularly when pyrimethamine (the active ingredient contained in Daraprim) is given in combination with a sulfonamide.


Oncologic side effects have included two reports of malignancy; both were associated with pyrimethamine (the active ingredient contained in Daraprim) treatment for toxoplasmosis: 1 patient developed chronic granulocytic leukemia after 2 years of therapy and 1 patient developed reticulum cell sarcoma after 14 months of therapy. Animal studies have revealed increased lung tumors with intraperitoneal administration.

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