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Some widely used medications can make you far more sensitive to summer’s sunlight and heat than you’d usually be. For example:

● Certain over-the-counter and prescription antihistamines and common antidepressants reduce your ability to sweat, which makes it difficult for your body to regulate its temperature properly. That makes you more prone to muscle cramps, heat exhaustion and heat stroke, which can rapidly escalate into an emergency.

●Diuretics such as chlorothiazide (Diuril and generic) and furosemide (Lasix and generic) may increase urine output, boosting the likelihood of dehydration.

●The antibiotic doxycycline (Doryx and generic) may increase your risk for painful, sunburnlike or itchy rashes, which can appear within minutes of sun exposure. Effects can include blistering, and they can linger long after you stop taking the drug.

●Topical pain relievers such as diclofenac (Flector, Pennsaid, Voltaren and generic) can lead to a rash that develops 24 hours to several days after you’ve been in the sun.

●The diuretic hydrochlorothiazide (HydroDiuril and generic) in combination with sun exposure can cause hyperpigmentation (permanent dark patches on your skin), says dermatologist Jessica J. Krant, a member of Consumer Reports’ medical advisory board.

Five smart strategies

Know your meds. Ask your doctor whether the medications or supplements you use make you more sun- or heat-sensitive, and check warnings on labels and package inserts. Also ask whether you can take such medication at night, which may reduce the chance of a reaction.

Keep yourself hydrated. Sip nonalcoholic liquids throughout the day, even if you don’t feel thirsty.

Be sun-safe. To reduce the likelihood of skin-related problems, use sunscreen daily, reapply it often and cover up when you’re outside during the day.

Stay cool. Do outdoor activities in the morning or evening, and seek refuge in air-conditioned rooms when it’s sweltering.

Know the signs of heat illness. If you develop a headache, racing pulse or rapid breathing, or if you feel lightheaded, nauseated or weak, lie down in a cool room with your feet above your heart. Apply wet cloths to your skin and drink a half-cup of sports drink or a solution of one teaspoon of salt in a quart of water every 15 minutes.

Safeguard your medicine

Heat and moisture can reduce the effectiveness of many medications, says Geoffrey C. Wall, a professor of pharmacy practice at Drake University in Des Moines, Iowa. For example, aspirin exposed to hot, humid conditions may break down into vinegar and salicylic acid, which can irritate your stomach.

Unless the label or insert indicates otherwise, store medicine in a cool, dry place, such as a secured box in a dresser drawer. And if you notice a change in the color, texture or smell of your medicine, or if tablets are stuck together, are harder or softer than normal or are cracked or chipped, dispose of them.

Copyright 2016. Consumers Union of United States Inc.

For further guidance, go to www.ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.