“Ishtar,” the notoriously bad movie classic starring Warren Beatty and Dustin Hoffman as musicians stumbling around the Moroccan desert, may have melted down because someone’s (or maybe several someone’s) medications couldn’t stand up to scorching heat.

Turns out, at temperatures above 86 degrees, many drugs lose their effectiveness — their active ingredients become less stable and less potent. So in this summer of heat waves and power outages, you want to make sure your important medications stay cool.

As a rule, drugs should be kept between 68 degrees and 77 degrees. They can go as low as 59 degrees or as high as 86 degrees for only brief periods of time. Everything from thyroid medications to antihistamines, statins and birth-control pills can fizzle with a summer sizzle. So remember:

Keep meds with you when you fly, not in checked baggage. And never put your meds in a car trunk.

Replace meds that get overheated. If your pharmacy has been without air conditioning for a while, it’s a good idea to get your prescriptions from someplace that stayed cooler!

Above 77 degrees in your house? Keep meds in a cool (not cold) case, away from ice or gel packs, and not below 68 degrees. A thermometer can help you maintain the right temperature.

PLUS! When temperatures climb, taking certain medications (antidepressants, antihistamines, high blood pressure meds or Parkinson’s drugs, for example) can constrict blood flow or reduce sweating. So stay cool and make very sure you drink plenty of fluids with your meds to avoid dehydration.

Mehmet Oz, M.D. is host of “The Dr. Oz Show,” and Mike Roizen, M.D., is chief medical officer at the Cleveland Clinic Wellness Institute. For more information go to www.RealAge.com.