With heavy heat suffocating much of the country, physicians aren’t just warning patients to keep themselves cool — they also want patients to prevent their medications from overheating.

Temperatures above 86 degrees Fahrenheit can render some medications useless, according to Robert Glatter, MD, an emergency medicine physician at Lenox Hill Hospital in New York.

“I’ve noticed an increase in the number of ED visits related to mental illness in the recent heatwave,” Glatter told MedPage Today, noting that most complaints have been related to anxiety or mood swings.

He said the effects could be tied to improper storage of medications in the heat, which may affect the bioavailability of the active agents in these drugs. The U.S. Pharmacopeia, a medication standards agency, states that drugs generally should be stored at room temperature — between 68 and 77 degrees Fahrenheit — with only brief excursions to temps as low as 59 degrees or as high as 86 degrees.

Above or below that, there’s no guarantee medications will work, the agency says.

Add to decreased efficacy the common problem of dehydration on high-heat days, and that makes for packed ED departments, Glatter said.

He said patients should be sure to keep their prescriptions with them in cool places, paying particular mind to where they’re stored during travel. That means keeping medications in pockets or purses when luggage gets tossed into cargo holds that might overheat, he said.