WASHINGTON  Manufacturers of pediatric cough and cold medicines announced Tuesday that they would voluntarily change their products’ labels to say that they should not be used in children under age 4.

In addition, products with certain antihistamines will get new language warning parents not to use them to sedate or make a child sleepy. While many parents believe that getting a sick child to sleep is the best medicine, the use of sedatives is widely discouraged by medical experts, who say they can worsen breathing problems caused by illness.

“We’re trying to prevent as many medication errors as we can, and we think this is the right direction,” said Linda A. Suydam, president of the Consumer Healthcare Products Association, a trade organization that represents the makers of over-the-counter medicines.

Officials at the Food and Drug Administration said they supported the changes, but promised to continue a long process to reassess the safety and effectiveness of the products in children of all ages.