Scorching days promise to continue in Southern California, with August generally the region’s hottest month. High temperatures, alone, increase the risk of heat-related illness. However, people who take many common medications face even greater danger of suffering serious health effects. Since they typically take multiple medications, people age 65 and older and those with chronic health conditions may be especially vulnerable.
“Medications can amplify the risk of heat to the body by interfering with the body’s thermal regulation and fluid balance,” says Ghada Ashkar, PharmD, associate chief of ambulatory pharmacy for UCLA Health. “Both of these mechanisms interfere with the body’s ability to cool itself.”
Mark Morocco, MD, clinical professor of emergency medicine at the David Geffen School of Medicine at UCLA, describes how the process works:
“The primary response to heat is sweating and the evaporative loss of heat. Sweating allows the air to create a natural cooling system, which is spread out over the skin, the body’s largest organ,” he says. “Some medications can decrease the ability to sweat. Others can increase the body’s heart and metabolic rates, causing the body itself to create heat in addition to the heat in the environment.”
Medications affecting the body’s ability to cool itself
Dr. Ashkar notes that several types of heart medicines decrease the body’s cooling mechanisms.
ACE inhibitors increase the risk of fainting and falling and may inhibit the sensation of thirst. Calcium channel blockers, used to decrease blood pressure, can cause electrolyte imbalances, which interfere with temperature regulation. Because beta-blockers decrease blood flow to the skin, they may make it harder for individuals to tolerate elevated temperatures.
Some antidepressants and antipsychotics may affect the hypothalamus, interfering with the body’s ability to regulate temperature and cool itself, Dr. Ashkar says. Some antidepressants may also affect the sensation of thirst or may prevent the sweat glands from functioning properly.
Diuretics, or water pills, are prescribed to treat conditions including heart failure, high blood pressure, and liver and kidney disease. Prompting the body to release extra fluids, diuretics can lead to dehydration and electrolyte imbalances.
Many antihistamines and decongestants interfere with the body’s ability to sweat.
ADHD medications raise the heart and metabolic rates, increasing the body’s production of heat.
Cooling techniques and danger signs
“The progression of heat-related illness can be subtle,” Dr. Morocco says. “It can quickly advance from feeling overheated and sweating profusely to heat stroke.”
When feeling overheated, he advises, get out of the heat and into an air-conditioned location. Or take a cool shower or get in a pool if possible.
Dr. Ashkar recommends drinking a lot of water, staying in the shade if feasible and applying cold compression to the skin.
Hydration needs vary by person, activity level and humidity. People who take medications should speak with their health care provider as they might have fluid restrictions.
As a general guideline, individuals should consume 1/2 to 1 ounce of water per pound of body weight each day. Those playing sports or working outdoors in hot weather should aim for a minimum of 1 ounce of fluid per pound of body weight.
Dr. Ashkar says the electrolyte solutions in sports drinks can help, but she advises avoiding those with caffeine or high amounts of sugar.
As diuretics, both caffeine and alcohol interfere with the body’s ability to cool itself. “People having alcohol may think they’re drinking, but they’re not hydrating,” Dr. Ashkar says.
Individuals need to be aware of alcohol’s effect and supplement their alcoholic drinks with water.
“When someone gets to the point that their brain is affected – they are confused, have a serious headache, feel dizzy or like they might pass out – that’s when it’s time to get them to a hospital or call 911,” Dr. Morocco says.
Prevention is key
“People on prescription medications need to speak with their doctor or pharmacist before the heat wave hits. Those health professionals can advise as to the person’s specific case and condition,” says Dr. Morocco.
“Just as important, they should make a pre-plan for how to avoid or minimize heat exposure during a heat wave,” he says. “People living alone should have a buddy who can check on them and take them to a cooler location if necessary.”
Prevention also includes keeping medications at appropriate temperatures.
Insulin, inhaler solutions and thyroid medications need to be kept at a cool temperature (68-77 degrees Fahrenheit). Insulin should be kept in the refrigerator until ready to use (it can remain at a cool temperature outside the refrigerator for 28 days once in use by the patient). And all medications must be kept away from direct sunlight and heat sources. Dr. Ashkar suggests storing them in a bedroom closet or drawer.
“When needing to carry medications along to a warm location, take an ice pack to help keep the medications cool,” she advises.
Bottom line
“Prevention in the form of having a plan for keeping cool is essential,” Dr. Morocco says. “But if someone gets to the point of being confused, it’s time to seek help.”
