Preventive Therapy

In addition to symptomatic treatment, people with frequent, debilitating headaches may prefer to try and prevent the headaches with preventive, or prophylactic, agents. Preventive treatment is usually recommended for migraine equivalents, migraine with aura, or complicated migraine, due a small increased risk of stroke in these patients.

Prophylactic therapy requires taking medication every day. More than one agent may be required. All of the preventative medications were originally developed for other conditions and later shown to be effective for migraine, specifically, antidepressants, medications for treating epilepsy, and medications for high blood pressure.

Anti-epileptics Sodium valproate 
(Depakote), topiramate (Topamax), and gabapentin (Neurontin) and others
Initially marketed for the treatment of epilepsy, these drugs are also useful in the treatment of headache. The dose is typically much lower than when used for seizures. Valproate can cause tremor, hair loss, stomach upset, and sedation but is better tolerated in the long-acting preparation. It rarely causes bone marrow problems and liver malfunction. Topiramate may produce sedation, trouble thinking clearly, weight loss, tingling, kidney stones (rarely), and sudden glaucoma. Sedation and confusion are possible side effects of gabapentin.
Anti-inflammatory drugs
Higher risk of ulcer or intestinal bleeding or liver problems with chronic daily use.
Aspirin
Daily aspirin works by preventing platelets from adhering to each other and affects serotonin levels. A low dose (one 325 mg adult aspirin or one 80 mg aspirin) daily is often effective. It should be taken on a full stomach. Daily aspirin may cause easy bleeding and bruising, and should be discontinued at least three days prior to surgery or dental work. Aspirin can also cause an ulcer, and should be avoided in people with pre-existing ulcer disease. Coated aspirin may help with 
stomach irritation.
Beta blockers propranolol (Inderal), 
nadolol (Corgard)
This group of drugs has been a mainstay of migraine prevention for many years. Some headache specialists caution against their use with basilar-type migraine,
 so they are not usually used as a first-line agent in these patients. The medication has to be taken two to four times daily, but long-acting preparations can be used when the optimum dose is found. The most common side effects are sleepiness, fatigue, low blood pressure, and sexual dysfunction. These medications cannot be used in people with asthma or congestive heart failure, and should be used with caution in diabetics.
Calcium channel blockers verapamil, amlodipine (Norvasc)
These medications work by stabilizing blood vessel walls to prevent spasm. They are most useful to complicated migraine/migraine equivalents, especially for transient visual loss in one eye. They are also effective for migraine headaches. They are taken two to three times daily, and long-acting preparations are available. Side effects include dizziness, swelling, and constipation. These drugs cannot be used in people with an abnormal heart rhythm, liver disease, or
 kidney disease.
Onabotulinum toxin (Botox)
Injections are used successfully in many patients who do not have relief with other preventive treatments. They are FDA-approved for the treatment of chronic migraine.
Other antidepressants Fluoxetine (Prozac), venlafaxine (Effexor), bupropion (Wellbutrin), and others
Often helpful alone or in combination with other preventative medications. They have an effect on headache, independent from the antidepressant effect, but are also helpful for people with headaches and mood disorders. As a group, common side effects include tremor, stomach upset or nausea, and vivid dreams.
Other treatments
Vitamin B2, co-enzyme Q, magnesium, PetadolexTM, or feverfew supplements may be beneficial. Nerve blocks are also employed for both acute and preventive treatment. Atypical antipsychotic medications and other antihypertensive drugs are effective in some patients. Surgery, such as occipital nerve stimulation, may be used for patients who do not improve with other therapies.
Tricyclic antidepressants amitriptyline (Elavil), nortriptyline (Pamelor), protriptyline (Vivactil)
After they were marketed for depression, these medications were found to be very effective in various neurological pain syndromes, including headaches and migraine phenomena. They are usually effective for migraine in much lower doses than those used for treating depression. To avoid excessive sedation, these medications are usually introduced in low doses at bedtime and gradually increased. The most common side effects include sedation (especially with amitriptyline) or insomnia, dry mouth, constipation, rapid heart rate, and weight gain.
 Most patients notice that they get a headache if they miss a dose. These drugs should not be stopped suddenly, if possible.