US health regulators have approved a weight-loss pill for the first time in 13 years.

Belviq, made by Arena Pharmaceutical, can be used by obese or overweight adults with at least one condition.

The drug achieved only modest results in clinical studies, helping people lose on average about 5% of their body weight.

Belviq was rejected in 2010 because of concerns over tumours that developed in animals tested with the drug.

After San Diego-based Arena resubmitted its application with more data, the US Food and Drug Administration (FDA) found little risk of tumours in humans using the drug.

Side effects

The medication is expected to launch in 2013.

Belviq is designed to block appetite signals in the brain, making patients feel fuller with smaller amounts of food.

Image caption Belviq is not recommended for women who are pregnant or nursing

It has been approved for use in obese adults with a body mass index of 30 or greater.

The drug can also be used by overweight adults with a BMI of 27 or greater if they have at least one other condition such as high blood pressure, type 2 diabetes or high cholesterol.

The FDA warned that Belviq is not for women who are pregnant or nursing.

With US obesity rates approaching 35% in adults and associated healthcare costs on the rise, many doctors have urged health regulators to give the green light to new weight-loss treatments.

But the agency has set high standards for such medication after safety problems with previously popular weight-loss drugs.

The so-called fen-phen combination had to be pulled from the market in 1997 after being linked to heart valve damage.

In a statement , the FDA said Belviq did not appear to carry the same risks.

However, known side effects of Belviq do include depression, migraine and memory lapses.

The FDA-approved label says the drug should not be used for more than 12 weeks if a 5% weight loss does not occur.

Arena will be required to conduct six studies after marketing the drug, including a study on the drug's effect on long-term heart health.