CHAMPAIGN – Migraine sufferers know what's coming when they start to get a headache: the hammering pain in the head, the nausea and the driving need to block out light and sound that makes the pain worse.

Some people take medicines to try to prevent the attacks and some treat the pain when it hits, and for some people, nothing seems to work very well.

Now doctors have another option to try to prevent these monster headaches for people who get them on a chronic basis: Botox injections.

But don't expect Botox treatment for migraines – approved by the U.S. Food and Drug Administration Friday – to be widely available to everyone.

Doctors say Botox, most commonly recognized as a cosmetic treatment for frown lines, is likely to be used on a selective basis for migraine patients only when other treatments fail.

And the cost – about $1,000 a month – could make it unaffordable for many, especially if insurers balk at covering it.

"I think it's worth trying," said Christie Clinic neurologist Dr. John Helfrich. "But I think there's going to be rigid criteria."

The FDA approved the use of Botox injections only to treat chronic migraine headaches – occurring for four hours a day or longer, 15 days a month or more – for people 18 and older.

To help dull the symptoms of future migraine attacks, Botox would be given about every three months in multiple injections around the head and neck, according to the FDA.

For less frequent migraine sufferers: Botox hasn't been shown to work as a treatment for those experiencing migraines 14 days a month or less.

More than 29.5 million Americans suffer from migraines, with women three times more likely to be affected than men, according to the National Headache Foundation. About three-quarters of the time, people with migraines have a family history of migraine.

Migraines typically come with intense pain in one area of the head, and often with a sensitivity to light and sound. Some people also experience nausea or vomiting.

Carle neurologist Dr. Robert Cranston says Botox for migraine prevention has been used off-label for some time – though not by him, because many patients with 15 or more migraines a month who have tried it have only experienced a reduction of a couple of migraines a month.

"I haven't been real impressed with the numbers," he said.

Cranston, also head of medical subspecialties at Carle, said insurers may offer coverage of Botox for some migraine patients, but are likely going to want to see proof that less expensive treatments haven't worked.

He, too, views Botox as a treatment that will largely fill a niche for patients for whom all other treatments have failed.

Helfrich said migraine treatments generally fall into those that help prevent migraines and rescue drugs to relieve pain. Analgesic pain-killers also offer some relief for some patients with occasional migraines, he said.

But pain relievers don't come issue-free, he adds. Frequent analgesic users often fall into a cycle of rebound headaches spurred by the drugs they take, and some prescription treatments come with black box warnings and aren't for everyone.

Botox maker Allergan Inc. says FDA approval for migraine treatment is one of several uses beyond cosmetic that have been approved for Botox in recent years. Others include treatments for:

– Increased muscle stiffness in elbow, wrist, and finger muscles with upper limb spasticity in people 18 and older.

– The abnormal head position and neck pain that happens with cervical dystonia in people 16 and older.

– Certain types of eye muscle problems (strabismus or "crossed" eyes) or abnormal spasm of the eyelids (blepharospasm) in people 12 and older.

– The symptoms of severe underarm sweating in people 18 and older, when medicines used on the skin don't work well enough.