People with frequent — sometimes daily — migraines may benefit from a new class of medications intended to prevent these severe headaches before they start, two new studies suggest.

Both of the studies tested "long-acting" drugs that were administered as injections once a month, to once every three months. The drugs — called fremanezumab and erenumab — appeared to be effective at preventing patients' migraines: The average number of monthly headaches was cut in half for up to 50 percent of the participants. What's more, the patients who took the drugs saw improvements in their ability to carry out everyday activities and were less physically impaired by their migraines.

However, more research is needed to look at the long-term safety and effectiveness of these drugs, and neither drug has been approved by the U.S. Food and Drug Administration.

This new class of drugs is "very exciting," said Dr. Kevin Weber, a neurologist and headache specialist at The Ohio State University Wexner Medical Center, who was not involved with the studies. "They're the first ever medications ever created just for the prevention of migraines and headaches," Weber said. These medications also appear to have very few side effects, and take only a short time to show an effect, he said.

Still, he added that it's important to temper patients' expectations about these drugs.

"They're not a 'miracle drug.' They're not going to cure everyone's headaches," Weber told Live Science. Although some participants did become headache-free after the treatment, they were in the minority. But these drugs are "another option for people who've failure a lot of other treatments," Weber said. [Ouch: 10 Odd Causes of Headaches]

The study of fremanezumab was funded by Teva Pharmaceutical, and the study of erenumab was funded by Amgen and Novartis.

Migraines can cause severe, throbbing or pulsing pain in the head, as well as sensitivity to light and sound. About 18 percent of people worldwide experience a migraine in their lifetimes, and 2 percent experience chronic migraine, in which attacks occur almost daily, the researchers said. Although there are some existing medications to prevent migraines, these medications were developed for other conditions — such as cardiovascular disease, depression and seizures — and they usually need to be taken daily.

In the new studies, the researchers tested medications that were specifically developed to target molecules that are thought to be involved in migraines. The drugs act against a small protein called calcitonin gene-related peptide (CGRP), which is produced in nerve cells. It's thought that, when CGRP is released around nerve cells in a person's head, it causes inflammation of tissues as well as expansion of blood vessels, which may lead to the pain of migraines, according to the American Headache Society. (The exact causes of migraines still aren't fully understood, according to Mayo Clinic.)

Both fremanezumab and erenumab are CGRP-blocking drugs — fremanezumab blocks the molecule itself, while erenumab blocks its receptor.

In one study, researchers tested fremanezumab for the prevention of chronic migraine, which is defined as severe headaches that occur at least 15 days per month. Of the 1,130 patients in the study, about one-third received the drug once a month for three months; one-third received a single dose of the drug over a three-month period; and one-third received placebo injections over the three-month period.

At the end of the study, those who received fremanezumab experienced about four fewer headaches per month, on average, compared with the number of headaches they had had at the start of the study; while those in the placebo group experienced about two fewer headaches per month, on average, compared with the number of headaches they had had at the start of the study. In addition, about 40 percent of the participants who received fremanezumab saw at least a 50 percent reduction in their average number of monthly headaches.

In the second study, the researchers tested erenumab in patients with "episodic migraine," meaning they had between four and 15 migraines per month (but no more than 15 headaches per month). The study involved 955 patients who were divided into three groups: One group received a low dose of the drug once a month; one group received a high dose of the drug once a month; and one-third received placebo injections once a month.

After six months, those who received erenumab experienced three to four fewer days with migraines per month, compared with the number of migraines they had experienced at the start of the study; while those in the placebo group had about two fewer days with migraines per month, compared with the number they had had at the start of the study.

"This therapeutic approach offers new hope for people whose migraines cannot be treated with existing medicine," Dr. Stephen Silberstein, lead author of one of the studies and the director of the Jefferson Headache Center at Thomas Jefferson University Hospital in Philadelphia, said in a statement. "If approved, this treatment would provide physicians with an important new tool to help prevent migraine," Silberstein said.

A treatment to prevent migraines that is targeted toward a possible underlying cause of migraine is "an important advance for patients," Dr. Andrew Hershey, director of the Division of Neurology at Cincinnati Children's Hospital Medical Center, wrote in an editorial accompanying the studies. Hershey was not involved in either study. These drugs may be useful for treating patients with migraines who haven't responded to other treatments, Hershey said. However, more research is needed to determine whether the effects seen in the studies last over the long term, he said.

Both studies were published Nov. 29 in The New England Journal of Medicine.

Original article on Live Science.