Manufactuers whose combination pain relief products contain acetaminophen will have to cap dosages and warn consumers about the risk for severe liver injury, the Food and Drug Administration announced today.

The new guidelines are meant to render prescription combination pain medications safer. Acetaminophen, the pain and fever-relief medication found in over-the-counter products like Tylenol, is sometimes combined in prescription products with other ingredients like codeine and opiods, such as oxycodone (Percocet) and hydrocodone (Vicodin).

“Overdose from prescription combination products containing acetaminophen accounts for nearly half of all cases of acetaminophen-related liver failure in the United States; many of which result in liver transplant or death,” Sandra Kweder, M.D., deputy director of the Office of New Drugs in FDA’s Center for Drug Evaluation and Research (CDER), was quoted in an FDA press release as saying.

Dosages will have to be capped at 325 milligrams and warning labels posted on boxes. The changes will be phased in over three years. According to the FDA, patients taking combination pain medications now are not in immediate danger. Liver injury typically occurs when patients exceed a maximum dose of 4,000 milligrams in a 24-hour period by taking multiple products that contain acetaminophen.

For more information: www.fda.gov/acetaminophen

Juliana Keeping is a health and environment reporter for AnnArbor.com. Reach her at julianakeeping@annarbor.com or 734-623-2528. Follow Juliana Keeping on Twitter