Accutane, a new drug that cures the most severe forms of acne, is being overprescribed and has begun causing a wave of severe side effects ranging from blindness to birth defects, the Health Research Group charged yesterday.

The group and some other doctors said that the drug, prescribed by 90 percent of U.S. dermatologists in its first year, possibly is being given to patients with acne not severe enough to warrant its use, thus putting more people at risk.

The drug's manufacturer, Hoffman-La Roche Inc., denied that the drug is being overprescribed. According to spokesman Carolyn Glynn, "This drug does have a very high side-effect profile . . . . The drug has tremendous benefits for patients, but they will also suffer from risks."

She said the company has been aware that side effects could show up, and from the outset has warned doctors to look out for them and to avoid prescribing the drug to pregnant women.

According to figures the Ralph Nader-affiliated Health Research Group collected from the Food and Drug Administration, 28 cases of severe reactions, including possibly two deaths, have been reported to the agency in the first year the drug has been on the market.

In addition, Dr. Frank Yoder of Ohio State University and the Columbus Children's Hospital, said another, longer-term effect of the drug may be a type of arthritis in which a person's backbone calcifies and tends to stiffen.

Yoder, who did the only large clinical test of the drug in humans, said, "I really feel the drug has been fantastically overpromoted for the number of patients that should be treated with it." The drug, he said, is intended only for cystic acne, the most severe type.

At the FDA's request, Hoffman-La Roche has sent a letter to 500,000 doctors and pharmacists as it became apparent that birth defects were turning up in the babies of women who had taken the drug while pregnant. Another letter was sent when cases of so-called pseudo-tumors, a condition that mimics brain tumors and can cause blindness, were first reported.