When you’re out enjoying a beautiful, warm summer day, your medication is probably the furthest thing from your mind. But as temperatures climb, it's a good idea to add reviewing your prescriptions to your summer safety checklist.

While many of us know the basics of staying safe while having fun in the sun, you may not know that your prescription could be increasing your risk of heat-related illnesses. This is because certain drugs, both prescription and over the counter, can interfere with thermoregulation, which is your body’s natural ability to control its internal temperature. In hot, sunny, humid weather, you become more vulnerable to dehydration, severe sunburn, heat exhaustion and heat stroke.

Below, we’ll discuss the signs and symptoms of both heat exhaustion and heat stroke, the medications that can increase your risk, and what you can do to stay safe through summer’s heat.

The causes of heat exhaustion, heat stroke and other heat-related illnesses

While our resting body temperatures can vary slightly, the generally accepted average is 98.6 degrees Fahrenheit. As soon as our internal body temperature begins to rise above this level, our brain wants to cool us down. It sends signals to our sweat glands to make us sweat and tells our circulatory system to start pumping blood to the surface of the skin where heat can escape.

Our reactions to heat put a huge strain on the body, and we can only keep things up for so long before fatigue sets in. If your body is doing everything it can to cool down, but its internal temperature is still rising, you run the risk of heat exhaustion and heat stroke.

What is heat exhaustion?

As your body tires and runs out of fluids, heat exhaustion sets in. Heat exhaustion usually doesn’t require medical treatment, but it’s still serious because it’s a precursor to heat stroke. If you or a loved one starts to experience any of the following symptoms, get out of the heat right away:

  • Muscle cramps
  • Headache
  • Nausea
  • Fatigue
  • Dizziness or confusion
  • Excessive sweating with cold, clammy skin

Find a spot in the shade or somewhere with air conditioning, take small sips of water, lie down with your feet above your head, and set cool cloths on your body to bring your temperature down.

What is heat stroke?

Heat exhaustion can become heat stroke if you don’t cool down within one hour of first showing the symptoms above. When your body loses control of its internal temperature, that is heat stroke – an emergency that requires immediate medical treatment. When spending time in the heat, watch out for these symptoms:

  • Hot, dry skin with an absence of sweating
  • Fast, shallow breathing
  • Rapid heart rate
  • Confusion, irritability or slurred speech
  • Poor balance
  • Loss of consciousness
  • Seizures (in severe cases)

If you think someone is suffering from heat stroke, call 911 immediately. While you wait for help to arrive, do everything you can to bring their body temperature down: get them out of the sun – preferably somewhere with air conditioning – and place ice and wet cloths on their skin, spray them with cold water or put them in a bathtub full of cool water.

The types of drugs that can increase the risk of heat exhaustion, heat stroke and other heat-related illnesses

Our ability to respond to hot weather is essential to our health, but what happens when these physical responses are disrupted? The following drug classes can alter your natural reactions to sun and heat, putting you at greater risk of experiencing a heat-related illness.

Psychiatric medications can interfere with communication between the brain and body

Certain psychiatric drugs can change the function of a part of the brain called the hypothalamus, which controls your body temperature and thirst, among other things. As a result, your brain can’t effectively communicate to your body that you’re overheating or getting thirsty. This can cause you to sweat too much or too little and become dehydrated.

Keep this in mind if you’re currently taking tricyclic antidepressants, antipsychotics, SSRIs, SNRIs or benzodiazepines.

Antibiotics can increase the risk of sunburn

Some antibiotics can make your skin more sensitive to the sun. This is called drug-induced photosensitivity, and it makes you more likely to get a rash or a severe sunburn – the kind that peels and blisters – following sun exposure.

If you are currently taking fluoroquinolone, sulfa antibiotics (including Bactrim) or tetracyclines (including doxycycline, minocycline and demeclocycline), use extra caution when spending time in the sun. In rare cases, amoxicillin can also make you more sensitive to sun exposure.

Topical acne medicine can make skin more vulnerable to the sun

Topical acne treatments help speed up renewal of the skin’s surface, but this temporarily thins the outer layer of skin, making us more vulnerable to the sun’s rays. Try to avoid prolonged sun exposure, use sunscreen and wear protective clothing if you regularly apply treatments containing benzoyl peroxide, retinol or salicylic acid to your skin.

Antihistamines can inhibit your ability to sweat

Antihistamines can stop your runny nose caused by allergies, but the same response that dries your nasal passages can dry everything else. This will prevent you from sweating as much as you normally would in hot conditions, leaving you without your body’s main defense against the heat. Benadryl and Dramamine can both limit your ability to sweat. Newer antihistamines, like Zyrtec and Claritin, won’t affect you this way.

Heart and blood pressure medication can hold in body heat and make it harder to sweat

Heat is hard on your heart. And if you’re currently taking heart or blood pressure medication, your heart may have to work even harder to keep you cool on hot days. Beta blockers lower your blood pressure and constrict blood vessels, making it more difficult for your body to pump blood to the surface of your skin and keep it there. And because diuretics flush excess liquid and sodium from your body to improve blood pressure, you may not be able to sweat enough in the heat.

Stimulants can raise resting body temperature

Stimulants raise your basal body temperature, which is the temperature your body maintains while at rest. With a higher resting body temperature, it takes less time and lower outdoor temperatures to make your core temperature shoot up to dangerous levels.

This is common with prescription stimulants used to treat ADHD, like Adderall and Ritalin. The same thing can happen with illegal stimulants, like cocaine, ecstasy and amphetamines.

Dehydration can affect how well medicine works in the body

Most of us take medication with water, and doing so actually helps drugs work the way they should. Drinking plenty of water helps medicines move through your stomach and into your intestines, where they can be absorbed. Being dehydrated prevents your body from properly absorbing medicine in the right amounts.

No matter the season, most doctors recommend drinking a full 8-ounce glass of water each time you take your oral medication.

Exposing medication to high temperatures

Most pill bottles list a range of temperatures at which the medicine inside can be safely stored, usually between 59-77 degrees Fahrenheit. Exposing either prescription drugs or over-the-counter medicine to high temperatures and humidity for long periods of time can make them less potent – but isn’t likely to make them harmful.

However, special care must be taken when storing potentially lifesaving medication like nitroglycerin, which needs to work at a moment’s notice. Be sure to regularly monitor and replace medications like nitroglycerin and EpiPens.
To preserve your medications:

  • Don’t leave them in the car
  • Don’t store them in direct sunlight
  • Don’t keep them in your bathroom

The best place to store medication (unless the directions say to keep it refrigerated) is somewhere warm, dry and away from any direct light.

How to prevent medication-related heat exhaustion and heat stroke

There’s a lot to think about when you decide to venture outside in the heat, especially if you’re taking one of the medications listed above. However, summer safety can still be simple. Enjoy the season, and tolerate the heat waves, with a few added precautions:

  • Take frequent breaks in the shade or in an air-conditioned place
  • Drink water continuously throughout the day, even when you don’t feel thirsty
  • Regularly apply sunscreen with at least 30 SPF, and avoid the sun during the middle of the day, about 10 a.m. to 4 p.m.
  • Protect yourself from too much direct sun exposure by wearing wide-brimmed hats, sunscreen and long-sleeve shirts made from fabric with a high ultraviolet protection factor (UPF)
  • Consult your doctor before trying any new outdoor exercise in the summertime
  • Don’t change how you take your medication without talking to your doctor first

Your prescriptions should work for you and your lifestyle, not the other way around. If you find that your medication is keeping you from some of your favorite summertime activities, schedule an appointment with your primary care doctor. They can adjust your dose or help you find alternative medicines and treatments.