The use of beta blockers for the treatment of migraine began in the late '60's, when by accident migraine sufferers being treated for cardiovascular disease found that their migraine attacks lessened. Further research in the '70s led to propranolol being the first of this class of medications to be approved by the FDA for migraine prevention. Subsequently the FDA also approved the use of timolol. Several other beta blockers have been shown in research trials to also be effective for migraine prevention. These include metoprolol, nadolol and atenolol.
Beta blockers appear to act by helping to stabilize the blood vessels and limiting the tendency for the blood vessels to over-dilate. Other mechanisms may include reducing the excitability of the nervous system, effects on the serotonin and reducing anxiety (such as when speaking in front of a crowd).
People who have coexisting respiratory diseases such as asthma or chronic bronchitis may not be able to use these medications. Discuss this medication with your doctor if you also receive allergy shots. Side effects include low blood pressure and slow heart rate.
In general, do not stop beta blockers abruptly as it can cause a dangerous increase in heart rate. These medications should only be used under physician supervision. Allow at least 4-6 weeks of therapy to see an effect on migraine frequency.