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As summer temperatures and humidity rise, INTEGRIS Health cautions people taking certain prescription and over-the-counter medications that they may impair the body’s ability to stay cool. If you find yourself highly sensitive to the summer heat, it could be a sign of heat intolerance.

What is heat intolerance?

“Heat intolerance means your body has a reduced ability to regulate its temperature, which can lead to serious heat-related illness,” says Robie Harrington, Pharm.D., clinical pharmacy specialist in the emergency department at INTEGRIS Health Southwest Medical Center.

Medications that may increase heat sensitivity

Several commonly used medications interfere with the body’s natural cooling processes, including:

• Antihistamines (e.g., diphenhydramine, hydroxyzine): Can reduce the ability to sweat.
• Beta blockers (e.g., metoprolol, propranolol): May blunt cardiovascular response and impair vasodilation, a key mechanism for cooling.
• SSRIs/SNRIs (e.g., sertraline, fluoxetine, venlafaxine, duloxetine): Can impair thermoregulation and increase the risk of serotonin syndrome, a potentially life-threatening condition with symptoms ranging from agitation and shivering to seizures or death.
• Diuretics (e.g., spironolactone, torsemide, furosemide, hydrochlorothiazide): May cause dehydration, electrolyte imbalance and reduced ability to sweat.
• Stimulants (e.g., Adderall, modafinil): Increase metabolism and body temperature, which can lead to dehydration and decreased thirst.
• Antipsychotics/antidepressants (e.g., olanzapine, clozapine, risperidone, haloperidol): Disrupt the hypothalamus, affecting temperature regulation and sweating.
• Anticholinergics (e.g., oxybutynin, benztropine, scopolamine): Inhibit sweat gland activity.

Even common over-the-counter products including allergy medications, decongestants, pain relievers, herbal weight loss aids and caffeine-based supplements can worsen heat sensitivity or contribute to dehydration.

Who is most at risk?

According to Harrington, those at higher risk include:

• Young children, pregnant persons and older adults
• People with chronic conditions such as cystic fibrosis, diabetes, cardiovascular disease, Graves’ disease, multiple sclerosis or mental illness
• Individuals unaccustomed to hot environments
• Those with a history of heat exhaustion or heat stroke
• Individuals working or exercising outdoors
• Heat intolerance is a common symptom during perimenopause and menopause due to fluctuating and decreasing estrogen levels

Symptoms

Individuals who live with underlying health conditions may notice that as temperatures increase, symptoms simultaneously begin to worsen.

Symptoms of heat intolerance and heat sensitivity include:

• Feeling excessively hot in moderately warm temperatures
• Spells of exhaustion and fatigue in summer months
• Dizziness and nausea when outside for extended periods of time
• Excessive sweating followed by little or no sweating
• Rapid heartbeat coupled with feelings of confusion
• Muscle cramping and weakness
• General feelings of illness

“If symptoms occur, move to a cooler place, hydrate, and apply cool, wet cloths to areas like the neck and underarms,” says Harrington. “When your body can’t cool itself properly, especially in extreme heat, the risk of heat exhaustion or heat stroke rises. In the event of a heat stroke, call 911 immediately.”

Tips for staying safe in the heat

• Hydrate - Drink plenty of water throughout the day and limit alcohol and caffeine.
• Take breaks - Seek shade or go indoors frequently.
• Avoid peak heat - Plan outdoor activities during cooler hours.
• Dress smart - Wear light, breathable clothing.

Family members and caregivers should monitor loved ones on heat-sensitive medications. “Know what they’re taking and have a plan to help them cool down if needed,” Harrington advises.

INTEGRIS Health encourages anyone with questions about their medications to speak with their pharmacist. If you or a loved one is struggling with heat intolerance, it is important to contact your primary care provider for a medical evaluation.