NEW YORK — Both CVS and Walgreens said they are limiting how many children’s pain and fever medications customers can buy — the latest sign that pharmacies are struggling to keep up with demand for basic cold and flu remedies, as respiratory illnesses spike nationwide.

CVS is limiting customers to a “two product limit on all children’s pain relief products at all CVS Pharmacy locations and cvs.com,” a CVS spokesperson said in a statement. The spokesperson did not provide details on how the limit would be enforced, but said the move was done in the name of ensuring “equitable access for all our customers.”

Walgreens is also implementing an “online only” six-product limit on all over-the-counter pediatric fever reducers, including medicines like acetaminophen (Tylenol) and ibuprofen (Advil), a spokesperson said, a move the company blamed on “increased demand and various supplier challenges.” There is no current limit on in-store purchases at Walgreens.