Common psychiatric drugs can rapidly make children obese, according to a study published in the Journal of the American Medical Association, reported by The Associated Press.

Researchers observed 205 New York area kids ages 4 to 19 who had recently used the psych drugs Abilify, Risperdal, Seroquel or Zyprexa.

On average, children who took one of the four study drugs gained 10 to 20 pounds in almost 11 weeks (depending on the drug taken). Ten to 36 percent of the participants became obese. Research also linked the meds to high cholesterol levels.

But there’s something even more disturbing. Health officials estimate that the number of children using these drugs has soared to more than 2 million each year.

Jeff Bishop, a psychiatric pharmacist at the University of Illinois in Chicago, said researchers don’t know why these drugs cause weight gain. What they do know is that the medications increase appetite and affect how the body metabolizes sugar. Despite the side effects, drug makers consider these meds safer than older anti-psychotic drugs.

Read RH’s “ Tips for Parents With Overweight Kids.”