propylthiouracil at a glance
Medicine class
Thionamide antithyroid treatment
Main use
Control of hyperthyroidism
How it is taken
Tablet taken by mouth with water, following the prescription label
Important ingredient
The selected product contains lactose
What is propylthiouracil used for?
The selected product is licensed for:
Treatment and management of hyperthyroidism, where the thyroid produces excessive hormone.
How does propylthiouracil work?
Propylthiouracil inhibits thyroid peroxidase, interfering with iodine use and chemical coupling steps needed to make thyroid hormones. It does not immediately remove hormone already stored in the thyroid, so its clinical effect develops gradually.
propylthiouracil preparations and strengths
Tablet
Route: Oral
Strengths: 50 mg, 100 mg
How to take propylthiouracil
Take the tablets exactly as shown on the prescription label. Swallow them with a glass of water and ask a pharmacist or prescriber if the instructions are unclear. Do not stop treatment solely because symptoms improve.
The tablets are taken by mouth.
The selected product contains lactose.
Keep appointments for requested blood tests.
propylthiouracil side effects
Common or expected effects
- Feeling sick or vomiting
- Stomach upset
- Altered taste
- Headache
- Mild rash, itching or hives
- Hair loss
- Muscle or joint discomfort
Get urgent medical advice
- Fever, sore throat, mouth ulcers or infection symptoms, which may indicate a severe fall in white blood cells
- Yellow skin or eyes, loss of appetite, itching or right-sided upper abdominal pain, which may indicate liver injury
- Unexplained bruising or bleeding
- Breathing difficulty, coughing blood or other severe hypersensitivity features
- New rash with kidney, lung or joint symptoms, which may indicate vasculitis
propylthiouracil in pregnancy
Hyperthyroidism needs effective treatment during pregnancy because uncontrolled disease can harm both mother and baby. Propylthiouracil crosses the placenta and may affect the baby's thyroid, so treatment requires individual specialist assessment and close maternal, fetal and neonatal monitoring. Anyone planning pregnancy or who becomes pregnant should contact their prescriber promptly rather than stopping treatment independently.
propylthiouracil while breastfeeding
Propylthiouracil passes into breast milk, but breastfeeding is not automatically excluded. The prescriber should assess the individual situation, and the infant's development and thyroid function may need monitoring.
propylthiouracil interactions
Changes in thyroid status and direct effects on thyroid treatment can alter the response to other therapies.
Theophylline
Its requirements may change as thyroid function returns towards normal, so clinical review may be needed.
Digoxin
Its requirements may change as hyperthyroidism is controlled, so response and treatment should be reviewed.
Beta blockers
Their requirements may change as thyroid function normalises.
Radioactive iodine
Previous propylthiouracil treatment may reduce the effectiveness of radioactive iodine therapy, requiring coordination by the thyroid specialist.
Common questions about propylthiouracil
Answers are fully visible for fast scanning and source review.
How quickly does propylthiouracil start working?
It begins blocking new thyroid hormone production promptly, but symptoms and blood levels improve gradually because previously formed hormone must first be used up.
What should I do if I get a sore throat while taking propylthiouracil?
Stop taking it and seek urgent medical advice. A blood count may be needed to check for a severe reduction in infection-fighting white blood cells.
Can propylthiouracil damage the liver?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.