Cause

• The exact cause of migraine headaches is unknown. Many women note a correlation between migraines and their menstrual cycle. It is unknown why changes in estrogen or serotonin levels trigger migraines.
  
  

Dosage

• The typical dosage prescribed for migraine prevention ranges from 80 to 240 milligrams per day. The dosage is usually divided into several pills taken throughout the course of the day.
  
  

Side Effects

• Side effects include fatigue, nausea, dizziness, insomnia, and depression. Propranolol is contraindicated for use in patients with low blood pressure.
  
  

Theories/Speculation

• It has been suggested that propranolol eases the swelling of blood vessels in the brain resulting from excess serotonin production.
  
  

Warnings

• Propranolol is not effective for treating migraine pain. Propranolol must be taken daily and patients may need to take it for several months before noticing an improvement in the frequency of their hormonal headaches. Propranolol is not safe for use during pregnancy.