How Medications Affect Heat Tolerance and Sun Sensitivity
As temperatures rise this summer, it’s important to be aware of the many risks that hot weather can pose, especially for older adults. One risk that is often overlooked is how certain medications can affect the body’s ability to stay cool or increase its sensitivity to sunlight. Certain medications used to treat a variety of health conditions may contribute to these effects.
Understanding how your medications may affect heat tolerance and sun sensitivity can help you take simple steps to stay cool, hydrated and protected throughout the summer. Never stop or change a medication without speaking to your healthcare provider first. Instead, work with your care team to develop a plan for staying safe during hot weather.
Medications That May Affect Heat Tolerance
Certain medications can interfere with the body’s ability to regulate temperature, making it harder to stay cool during hot weather. Some may reduce sweating, affect blood flow, increase fluid loss, increase sedation/cognitive impairment or contribute to dehydration. Examples include:
- Diuretics (“water pills”), for high blood pressure, heart failure, and swelling
- Beta blockers and other heart medications, for high blood pressure, heart disease, and irregular heart rhythms
- Antidepressants, for depression, anxiety, and other mental health conditions
- Antipsychotic medications, for schizophrenia, bipolar disorder, and other mental health conditions
- Antihistamines, for allergies
- Anti-seizure medications, for seizure disorders and some types of nerve pain
- Stimulant medications for Attention Deficit Hyperactivity Disorder (ADHD)
- GLP-1 medications, for diabetes and weight management
Medications Known to Increase Sun Sensitivity
Heat isn’t the only concern during the summer months. Some medications can make your skin more sensitive to sunlight, a reaction known as photosensitivity. This can increase the risk of sunburn, rashes, skin irritation and long-term skin damage. Examples include:
- Some antibiotics, such as doxycycline and ciprofloxacin, used to treat bacterial infections
- Certain non-steroidal anti-inflammatory drugs (NSAIDS), such as naproxen used for pain, inflammation, and fever
- Some Diuretics, specifically hydrochlorothiazide, used for high blood pressure, heart failure, and fluid retention
- Certain antidepressants used to treat depression and anxiety, such as amitriptyline
- Several Retinoids, such as isotretinoin, used to treat severe acne
Note: Not all medications within these groups increase sun sensitivity. The risk varies depending on the specific medication. If you are unsure whether your medication may increase your sensitivity to the sun, talk to your doctor or pharmacist.
Who is Most at Risk?
Taking medications that affect heat tolerance or sun sensitivity does not mean you will experience problems in hot weather. However, your risk is higher if these medications are combined with other factors, such as:
- Being 65 years of age or older
- Having chronic health conditions such as heart disease, diabetes, kidney disease, or respiratory conditions
- Taking multiple medications that affect heat tolerance or hydration
- Spending time outdoors during the hottest part of the day
- Performing strenuous activities such as yard work or exercise in hot weather
- Having limited access to air conditioning or cool indoor spaces
Tips for Staying Safe in the Heat and Sun
If you are taking medications that affect heat tolerance or increase sun sensitivity, these simple precautions can help reduce your risk of heat-related illness or skin reactions:
- Drink plenty of water throughout the day, even if you don’t feel thirsty
- Limit sugary and alcoholic beverages, which can contribute to dehydration
- Stay in air-conditioned places whenever possible
- Close blinds and curtains during the day to help keep your home cool
- Open windows in the evening when outdoor temperatures are cooler
- Avoid strenuous outdoor activity between 10 a.m. and 2 p.m. or during extreme heat events
- Plan errands, walks, and yard work for the early morning or evening
- Wear lightweight, loose-fitting, light-coloured, long-sleeved shirts and pants, sunglasses and broad-brimmed hats.
- Seek shade whenever possible
- Use a broad-spectrum sunscreen (protection against ultraviolet A (UVA) and ultraviolet B (UVB)) with SPF 30 or higher, even on cloudy days
- Take cool showers or baths when you begin to feel overheated
- Store medications according to label instructions, away from direct sunlight and never in a hot car, as excessive heat may reduce their effectiveness
Know the Signs of Heat-Related Illness and Heat Stroke
Even with precautions, heat-related illness can still occur. It is important to recognize the early warning signs and act quickly. Seek medical attention if you or a loved one experiences symptoms such as:
- Excessive sweating
- Dizziness or lightheadedness
- Headache
- Muscle cramps
- Nausea or vomiting
- Weakness or fatigue
These may be early signs that the body is struggling to cope with the heat. Stop activity, move to a cool place, drink fluids, and seek medical help if needed. If symptoms worsen, heat stroke may be developing. Heat stroke occurs when the body can no longer control its temperature and can quickly damage the brain, heart, kidneys, muscles, and other organs if not treated immediately.
Call 911 immediately if someone develops symptoms such as:
- Confusion, delirium or unusual behaviour such as agitation or aggression
- Blurred vision or slurred speech
- Loss of consciousness
- Seizures
- High body temperature, typically over 40°C (104°F)
- A rapid heart rate or fast, shallow breathing
There is no one-size-fits-all approach to managing medications during hot weather. The effects of heat and sun exposure can vary depending on your age, health conditions, activity level, and the medications you take.
Talk to your doctor, nurse practitioner, or pharmacist if you have questions about how your medications may affect heat tolerance or sun sensitivity. They can help you understand your personal risk and recommend ways to stay safe during hot weather. By staying informed, taking simple precautions, and recognizing early warning signs, you can reduce your risk of heat-related illness this summer.
Reviewed By: David Yam, Lead Pharmacist, VHA Home HealthCare
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