At recommended dosage, adverse reactions have occurred rarely, except in patients with polycystic ovary syndromes where it may cause excessive responses.
In high doses (≥100 mg daily) or if the treatment is extended, adverse reactions have often occurred.
The most common adverse reactions are enlargement of the ovaries or ovarian cyst formation and vasomotor disturbances eg, hot flushes. Other adverse effects are abdominal/pelvic discomfort, sight disturbances eg, blurred vision, diplopia, scotomata, phosphenes, photophobia; nausea/vomiting; increase in frequency and volume of urine; increased appetite and body weight; various dermatological conditions including urticaria, rash or allergic dermatitis; breast tenderness; headache, nervousness, insomnia, dizziness, lightheadedness, depression, fatigue and hair loss.
These adverse reactions usually diminish or disappear if treatment is discontinued.