WHITEHOUSE STATION, N.J. (AP) — U.S. regulators have again approved a Merck & Co. tablet for gradually reducing seasonal allergies, this time for ragweed pollen.

Ragwitek tablets dissolve quickly under the tongue. Patients are to take one daily, from three months before ragweed season begins until it ends, for a few years. The Food and Drug Administration approved it for patients aged 18 through 65.