Propylthiouracil (PTU) (Propylthiouracil)
Also sold as: PTU, Propycil
Pregnancy
Cat D
Lactation
Safe
Schedule
H
Forms
Tablet 50mg
Indications
- Hyperthyroidism / Graves' disease
- Thyroiditis (thyroid storm)
- Thyroid cancer (preparation)
- PTU preferred in pregnancy (less placental transfer than methimazole)
Adult Dosing
Hyperthyroidism (initiation)
300-600 mg PO daily divided TDS
Initial 4-6 weeks to control
Hyperthyroidism (maintenance)
100-150 mg PO daily divided BID-TDS
Long-term maintenance
Thyroid storm (acute)
400-600 mg loading, then 200-300 mg Q4-6H
Acute setting with beta-blockers
Pediatric Dosing
Frequent monitoring needed; TSH/Free T4 every 4 weeks until euthyroid
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| CrCl any level | No specific adjustment; monitor response |
Hepatic Adjustment
Severe hepatic impairment: avoid or use with extreme caution.
Pregnancy & Lactation
Pregnancy: Category D
While category D, PTU is PREFERRED in pregnancy vs. methimazole due to lower placental transfer and lower teratogenic risk (methimazole associated with embryopathy). Use lowest effective dose; goal TSH 0.5-2.5 mIU/L.
Lactation: Safe
Minimal excretion in breast milk; generally safe.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| Warfarin | Increased anticoagulant effect as thyroid status normalizes | Moderate |
| Beta-blockers | May need dose reduction as hyperthyroidism controlled | Moderate |
| Theophylline | May need dose adjustment | Minor |
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Side Effects
Common
- Rash / urticaria
- Nausea
- Arthralgia
- Myalgia
- Fever
- Liver enzyme elevation
Serious / Discontinue If
- Agranulocytosis (0.1-0.5%)
- Hepatotoxicity / liver failure
- Lupus-like syndrome
- Vasculitis
- Thrombocytopenia
Contraindications
- History of agranulocytosis or severe hepatic reaction to PTU
- Severe hepatic impairment
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| PTU 50 mg | Various | 10 tab ₹40-60 |
| Propycil 50 mg | Cipla | 10 tab ₹50 |
Monitoring Required
- CBC (white cell count) at baseline, 1 month, then Q3 months (agranulocytosis risk)
- LFT at baseline, 1 month, then Q3 months
- TSH / Free T4 Q4 weeks until euthyroid, then Q2-3 months
- Symptoms of agranulocytosis (fever, sore throat)
Patient Counseling Points
- Report fever, sore throat, or unusual bruising immediately (agranulocytosis sign)
- Report jaundice or dark urine (hepatotoxicity sign)
- Take with food to reduce GI upset
- Regular blood tests essential (CBC, LFT, TSH)
- Goal: achieve euthyroid state, then transition to beta-blocker or radioactive iodine
- Pregnancy: discuss PTU preference with obstetrician
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Clinically reviewed by: Dr. Priya Desai, MD (Obstetrics & Endocrinology), High-Risk Pregnancy Specialist
Last reviewed: 2026-04-14
References
- BNF — Propylthiouracil
- American Thyroid Association 2024
- ACOG Thyroid in Pregnancy Guidelines