Updated

Companies that make fentanyl pain patches are being required to change the writing on the products so they can be seen more easily, after two more children who were accidentally exposed to the patches died.

Fentanyl is a narcotic sold in a variety of formats including a patch that is stuck to the skin. It is sold under the brand Duragesic by Johnson & Johnson. Generic versions are also available.

The U.S. Food and Drug Administration warned last April that fentanyl patches could cause life-threatening harm to children who were accidentally exposed to patches that may have fallen to the floor or been improperly discarded.

On Monday, the agency said it will require color changes to the writing on fentanyl patches so they can be seen more easily. Companies must print the name and strength of the drug on the patch in long-lasting ink, in a color that is clearly visible to patients and caregivers.

"The current ink color varies by strength and is not always easy to see," the FDA said in a statement. "This change is intended to enable patients and caregivers to more easily find patches on patients' bodies and see patches that have fallen off, which children or pets could accidentally touch or ingest."