A one-month-old baby is reportedly in the Hawke's Bay Hospital intensive care unit after it was given the wrong medication by a pharmacy.

The baby was taken to the hospital on Tuesday after it stopped breathing, Stuff has reported.

A Hawke's Bay District Health Board spokeswoman said the child was in a "serious-but-stable condition" and was recovering.

Stuff reported a pharmacy had mistakenly put methadone medication in a container that was meant to have the child's prescribed medication.