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Propylthiouracil Side Effects

For the Consumer

Applies to propylthiouracil: oral tablet

As well as its needed effects, propylthiouracil may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking propylthiouracil, check with your doctor immediately:

More common:
  • Black, tarry stools
  • chest pain
  • chills
  • cough
  • fever
  • painful or difficult urination
  • shortness of breath
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • unusual bleeding or bruising
  • unusual tiredness or weakness
Less common:
  • Dark-colored urine
  • general feeling of discomfort, illness, or weakness
  • headache
  • light-colored stools
  • nausea or vomiting
  • stomach pain, continuing
  • upper right abdominal or stomach pain
  • yellow eyes and skin
Incidence not known:
  • Abdominal or stomach pain
  • agitation
  • bleeding gums
  • bleeding under the skin
  • blood in the urine or stools
  • bloody or cloudy urine
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • coma
  • confusion
  • cough or hoarseness
  • cracks in the skin
  • decreased urine output
  • depression
  • difficulty with breathing
  • difficulty with moving
  • dizziness
  • drowsiness
  • feeling of fullness
  • fever with or without chills
  • general feeling of discomfort, illness, or weakness
  • high blood pressure
  • hostility
  • irritability
  • joint pain
  • lethargy
  • loss of appetite and weight
  • loss of heat from the body
  • lower back or side pain
  • muscle aching or cramping
  • muscle pain or stiffness
  • muscle twitching
  • numbness or tingling of the hands, feet, or face
  • pain in the ankles or knees
  • painful, red lumps under the skin, mostly on the legs
  • pinpoint red spots on the skin
  • rapid weight gain
  • red, swollen skin
  • redness, soreness, or itching skin
  • scaly skin
  • seizures
  • soreness of the muscles
  • sores on the skin
  • sores, ulcers, or white spots on the lips or in the mouth
  • sores, welting, or blisters
  • stupor
  • swelling of the face, ankles, hands, feet, or lower legs
  • swollen joints
  • swollen salivary glands
  • swollen, painful, or tender lymph glands in the neck, armpit, or groin
  • tightness in the chest
  • unusual weight gain
  • wheezing

If any of the following symptoms of overdose occur while taking propylthiouracil, get emergency help immediately:

Symptoms of overdose:
  • Bloody, black, or tarry stools
  • high fever
  • itching skin
  • pale skin
  • swelling

Minor Side Effects

Some propylthiouracil side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

Incidence not known:
  • Abnormal loss of hair
  • change in taste or bad unusual or unpleasant (after) taste
  • dizziness or lightheadedness
  • feeling of constant movement of self or surroundings
  • heartburn
  • hives or welts
  • loss of taste
  • pain or discomfort in the chest, upper stomach, or throat
  • sensation of spinning
  • skin rash
  • sleepiness

For Healthcare Professionals

Applies to propylthiouracil: oral tablet


Frequency not reported: Vasculitis syndrome associated with the presence of antineutrophilic cytoplasmic antibodies (ANCA)[Ref]


Rare (0.01% to 0.1%): Stevens Johnson syndrome, toxic epidermal necrolysis
Very rare (less than 0.01%): Skin rash, urticaria
Frequency not reported: Exfoliative dermatitis, erythema nodosum, abnormal loss of hair, pruritus, skin pigmentation, lightening of hair color, lymphadenopathy, mild papular skin rashes, cutaneous vasculitis[Ref]


Rare (Less than 0.1%): Vomiting
Frequency not reported: Nausea, vomiting, epigastric distress[Ref]


Rare (Less than 0.1%): Agranulocytosis, thrombocytopenia, leucopenia, aplastic anemia, pancytopenia, hemorrhage, granulopenia
Frequency not reported: Hypoprothrombinemia, lymphadenopathy[Ref]


Frequency not reported: Increase of decrease in urination[Ref]


Common (1% to 10%): Asymptomatic liver function test abnormalities (increased serum bilirubin, alanine transaminase and/or alkaline phosphatase concentrations), which are reversible on dose reduction or discontinuation of treatment
Frequency not reported: Liver injury (e.g., hepatitis, liver failure necessitating liver transplantation or resulting in death), nephritis, glomerulonephritis, jaundice (usually cholestatic), hepatic necrosis, hepatic failure[Ref]


Frequency not reported: Lupus-like syndrome (including splenomegaly and vasculitis), sialadenopathy[Ref]


Frequency not reported: Edema[Ref]


Frequency not reported: Periarteritis, arthralgia, myalgia, arthritis, myopathy, backache[Ref]

Nervous system

Frequency not reported: Paresthesias, loss of taste, taste perversion, headache, drowsiness, neuritis, vertigo, encephalopathy, numbness or tingling of fingers, toes, or face[Ref]


Frequency not reported: Fever, antineutrophil cytoplasmic antibodies (ANCA)[Ref]


Frequency not reported: Sore, red, watery eyes (recurrent keratitis, conjunctival disorders)[Ref]


Frequency not reported: Acute glomerulonephritis[Ref]


Frequency not reported: Interstitial pneumonitis, alveolar hemorrhage[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. "Product Information. Propylthiouracil (propylthiouracil)." Lederle Laboratories, Wayne, NJ.

3. Pharmaceutical Society of Australia "APPGuide online. Australian prescription products guide online. Available from: URL:" ([2006]):

It is possible that some side effects of propylthiouracil may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.