Oct. 10, 2014 -- The FDA on Friday approved the first combination pill to treat hepatitis C. The medication is so powerful it cures the disease for nearly all who take it.

The once-daily pill, called Harvoni, is a combination of the already approved drug sofosbuvir (Sovaldi) and a new drug called ledipasvir.

Many people with hep C have been eagerly awaiting the drug’s approval.

“I just wrote the first prescription for one of my patients -- who was waiting a year for this -- like a half an hour ago,” says Saleh Alqahtani, MD. He's the director of clinical liver research at Johns Hopkins Hospital in Baltimore. “It’s really amazing. I can’t believe it. My patient was so excited. Hopefully she can start it next week,” when the drug becomes available in pharmacies, he says. “It’s really a good drug.”

In clinical trials, Harvoni was so effective that it cured hepatitis C after 3 months of treatment in about 94% of people who took it. Cure rates approached 100% after 6 months of treatment in patients whose hep C was harder to treat, often because their livers had already been scarred by the disease, a condition called cirrhosis.

The drug is approved to treat chronic hepatitis C genotype 1, the most common type of infection. According to the CDC, 3.2 million Americans are infected with hepatitis C.

“There are no significant side effects with this drug. And no serious drug-to-drug interactions,” says David Bernstein, MD, chief of hepatology at North Shore University Hospital in Manhasset, N.Y.

In studies, the most common side effects reported by people taking Harvoni were fatigue and headache.

“It really brings us to the next level that we never thought we’d get to,” Bernstein says.

Harvoni also gets rid of the need for patients to take a weekly shot of interferon or a second antiviral medication called ribavirin, which is usually prescribed as a twice-daily pill.

Even people taking the newer drug Sovaldi must still pair it with one of those drugs.

Both interferon and ribavirin come with significant side effects, including fatigue and flu-like symptoms that many people find hard to tolerate. And only about half of patients who took those medications could expect to respond to them.

The medications in Harvoni are part of a new class of drugs called direct-acting antiviral agents, and they interfere with enzymes the hepatitis C virus needs to multiply.