When doctors began prescribing beta blockers for their patients with both high blood pressure and migraines, many of their patients noted that the frequency and intensity of the migraines lessened. Propranolol is a generic beta blocker often used off-label for treatment of migraines, whether or not the patient has high blood pressure.
According to "Pharmacologic Management of Acute Attacks of Migraine and Prevention of Migraine Headaches" (Snow, et al, Annals of Internal Medicine, 2002), it is unknown exactly how propranolol or other beta blockers helps people with migraines. It is also unknown exactly what causes migraines.
The recommended dosage to prevent migraines is between 80 and 240 milligrams per day. A patient must work up gradually to this dosage, as propranolol can have harsh side effects. Often, doctors will prescibe taking one 10 to 30 milligram tablet a day for a week and then gradually increase the dosage week by week to the desired dosage.
According to propranolol's manufacturers, it can give a variety of side effects, including excessive flatulence, cramping, diarrhoea, drowsiness, decreased sex drive and mild nausea. Serious side effects that need a prompt call to the doctor include inability to concentrate, confusion, sore throat, fever, swollen feet or ankles, always feeling cold in the hands and feet, dizziness, irregular heartbeats and breathing problems.
The worst of the side effects should be gone in two to four weeks. It can take a s long as three months to begin to get the benefit of the beta blocker. If the side effects are too disruptive before this time, then the medicine can be reduced, switched to another beta blocker or switched to another type of preventive, such as an antidepressant or a calcium channel blocker.
Propranolol has to be taken every day to prevent migraines. It will not help alleviate a migraine that has already started, because it does not have any pain killing properties. For migraine pain, over the counter NSAIDs are often effective if taken as soon as the patient realises a migraine has started. Prescription painkillers like triptans also can be effective.