Health checkup: Hot weather and medications
Weather-related heat illnesses are well known, but reports rarely address how medications can make people more sensitive to sunlight and less tolerant of heat. Knowing the effects of medications can prevent uncomfortable or dangerous reactions.
Two main reactions are a greater likelihood of sunburn and an increased risk of heat stress or heat stroke. These reactions can be caused by many medications. The ones that follow are examples.
Sunlight can interact with the diuretics hydrochlorothiazide and furosemide; antibiotics bactrim and tetracycline; nonsteroidal anti-inflammatory drug naprosyn; antipsychotics, chlorpromazine and haldol; and herbs including St. John’s wort. This interaction can lead to an immediate reaction that resembles an exaggerated sunburn or rash. This occurs on exposed skin, giving a clear delineation of shading caused by clothing.
Application of a broad spectrum sunscreen provides some protection against photosensitivity reactions, when applied correctly. Also, if you have to be in the sun, wear protective clothing.
Some medications also can inhibit sweating and reduce the body’s ability to regulate temperature. Such medications are antihistamines, antidepressants, pseudoephedrine, stimulants, diuretics, benztropine and beta-blockers. People who use these drugs and who are inactive as well as those who exercise when it’s hot and humid should know the symptoms.
Increased body temperature occurs along a continuum of heat-related conditions starting with heat stress, progressing to heat exhaustion then to heat stroke, which is a medical emergency.
Heat stress symptoms include mild discomfort, cramps and possibly dizziness. Heat exhaustion is manifested by gradual weakness, nausea, drenching sweats, pale, clammy skin, slow pulse, low blood pressure and feeling faint. Heat stroke is accompanied by anxiety, confusion, loss of coordination, agitation and often coma. Hot, red, dry skin with little sweating, rapid pulse and a high temperature are also present.
Most often, these medications need to be taken for chronic illnesses, so they should not be discontinued without the prescriber’s consent.
Being aware of these potential reactions, along with using suggested sun and heat precautions, can prevent complications. If you have questions, talk to the prescriber or your pharmacist.
Jane Sundberg, doctor of pharmacy, is a psychiatric clinical pharmacist at Strong Health’s department of pharmacy.
