Migraines are painful, throbbing headaches that last from 4 to 72 hours. They often occur on only one side of your head. But the pain may move from one side of your head to the other, or you may feel it on both sides at the same time. Migraines may be so painful that you aren't able to do your daily activities.

When you have a migraine, you may also feel sick to your stomach and vomit. Activity, light, noise, or certain smells may make your migraine worse.

Some people have an aura before their migraine starts. When you have an aura, you may first see spots, wavy lines, or flashing lights. Your hands, arms, or face may tingle or feel numb. The aura usually starts about 30 minutes before your headache. But most people don't have auras.

Migraines run in families. But it's not clear why some people get them and others don't.

The cause of migraines is not well understood. But experts think that it may have something to do with changes in the activity of brain cells. These changes may lead to inflammation of certain nerves, which then causes pain. Some things called triggers can cause migraines to start. Examples of triggers include certain foods, alcohol, and stress.

If your migraine symptoms are mild to moderate, doctors recommend that you first try over-the-counter pain medicines to manage your headaches. These medicines are safe and cost less than prescription migraine medicines. They include:

• Acetaminophen (such as Tylenol).
• Aspirin (such as Entrophen).
• Ibuprofen (such as Advil).
• Naproxen (such as Aleve).

If these medicines don't help, your doctor may prescribe a medicine that can quickly stop a migraine after it has started. A group of drugs called triptans is most often tried first. But these can cause serious side effects, especially for people who have heart disease and high blood pressure.

If over-the-counter pain medicines or triptans don't work, and if you get bad migraines often, you may want to take medicine to help prevent them.

There are several types of medicines that help prevent migraines. Some of these medicines were first approved to treat other medical problems such as seizures, depression, high blood pressure, and heart disease. But they also help to prevent migraines.

Medicines used to prevent migraines include:

• Anticonvulsants (antiseizure medicines).
• Antidepressants.
• Beta-blockers.
• Botulinum toxin, such as Botox. This may be used to prevent chronic migraines.
• CGRP antagonists.

Medicines to prevent migraines may not stop every migraine. But prescription medicines may reduce the number of migraines that you have. The medicine may also reduce how long a migraine lasts or make your symptoms less severe.

Botulinum shots can help reduce the number of migraines people have if they were having chronic migraines (more than 15 migraines a month) before treatment.

You may take pills every day—even when you don't have a headache. Or you may get regular injections or infusions of the medicine.

The medicine may be started at a low dose. Your doctor may increase the dose over time to find a dose that helps prevent migraines for you.

If you don't see any improvement after several weeks, talk to your doctor. You may need to take a medicine for a few months before it works well for you. Or you may need to try several different medicines to find one that works for you.

A medicine may not prevent all migraines, so there may be times when you need to take another medicine to stop a migraine after it has started.

Medicines to prevent migraines may cause side effects. Some of these side effects may last for as long as you take the medicine. Or they may go away within a few weeks. You may need to decide which bothers you more—the side effects of the medicine or your migraines.

Common side effects include:

• Sleep and memory problems.
• An upset stomach.
• Dry mouth.
• Constipation.
• Weight gain or loss.
• Fatigue.
• Dizziness.
• A fast heart rate.
• Problems at the injection site.
• A drooping eyelid (Botox).
• Bruising on the face (Botox).

Serious side effects can also happen. For example, anticonvulsants can cause birth defects if they are taken during pregnancy. Botox can cause severe weakness in the muscles of the face or head. In very rare cases, the botulinum toxin can spread and cause weakness in the muscles that control breathing or swallowing.

What else can you do to prevent migraines?

There are other things you can try to prevent migraines.

• Identify and try to avoid triggers, such as certain foods, alcohol, and smoking. It may help to keep a headache diary to track how often you have migraines, how painful they are, and what you think might be causing them.
• Have a healthy lifestyle. Exercise regularly, eat healthy foods, and get enough sleep. Avoid alcohol and drugs. Avoid foods that may trigger your headaches.
• Practice relaxation and breathing exercises, such as meditation, guided imagery, tai chi, or qi gong, to help reduce stress and relax your mind and muscles.
• Ask your doctor about device therapy. There are different kinds of these devices. They use an electrical current or magnets to change nerve activity.
• Try acupuncture. This involves putting very thin needles into the skin at certain points on the body.
• Try biofeedback. This is a way to control a body function—such as muscle tension—that you don't normally control.
• Talk with your doctor before you try supplements or natural health products, such as the herb feverfew, magnesium, or riboflavin (vitamin B2).

Why might your doctor recommend medicine to prevent your migraines?

Your doctor may advise you to take medicine to prevent migraines if:

• You get bad migraines often.
• Your migraines are so painful that you're not able to do your daily activities.
• You use medicine more than twice a week to stop a migraine after it has started.
• You have tried medicines to stop a migraine, but they don't help.