July is the hottest month of the year on average, and last year was the third-warmest July on record. July 2024 was the hottest month ever recorded. For people taking certain common medications, those temperatures carry added risk.
According to Healthline, at least 10 categories of medications can interfere with how the body handles heat. These include antidepressants, antipsychotics, GLP-1 medications, and beta-blockers. The drugs can cause problems through several different pathways, including reduced sensations of thirst, interference with thermoregulation, impaired sweating, reduced cardiac output, electrolyte imbalance, and cognitive impairment.
David Cutler, MD, a board certified family medicine physician at Providence Saint John's Health Center in Santa Monica, California, said awareness of drug interactions with heat is low. "People are all aware of the risks of overheating, dehydration, and sunburn. But they should all be more aware of how medications can cause intolerance to summer heat," Cutler said.
Antidepressants are among the most widely used medications in the country, and two common classes carry elevated heat risk. Selective serotonin reuptake inhibitors, known as SSRIs, and tricyclic antidepressants, known as TCAs, can both disrupt normal sweating patterns. The disruption can push the body toward either excessive sweating or sharply reduced sweating. Either condition makes it harder for the body to cool itself. Research from 2022 found that these antidepressant types can raise core body temperature to 106 degrees Fahrenheit, which increases the risk of heat exhaustion and heatstroke.
Cutler pointed specifically to medications that reduce sweating as the most dangerous in hot weather. "The most obvious effects of heat intolerance are seen in those taking medications which decrease sweating," he said.
Antipsychotic medications carry similar risks. Like antidepressants, antipsychotics can disrupt thermoregulation. They can also alter a person's perception and reduce their ability to sense that they are becoming dangerously overheated. Some antipsychotics, including lithium, add another hazard: dehydration-induced drug toxicity. Signs of lithium toxicity can appear when a person taking the drug becomes dehydrated in hot weather. Anyone experiencing those signs is advised to contact a healthcare professional right away.
Beta-blockers present a different mechanism. These drugs, commonly prescribed for heart conditions and high blood pressure, reduce cardiac output. That reduction limits the body's ability to increase blood flow to the skin, which is one of the primary ways the body sheds heat. The result is a reduced capacity to stay cool when temperatures rise.
The Healthline report noted that GLP-1 medications, a class that has grown rapidly in use due to drugs like semaglutide, also appear on the list. These drugs can reduce the sensation of thirst, which means people taking them may not feel the urge to drink water even as their body is becoming dehydrated in the heat.
Across all the medications identified, healthcare professionals advise people to take extra precautions during summer months. Those precautions include staying in cool environments, drinking water consistently rather than waiting to feel thirsty, and making a specific heat safety plan with a doctor. Sharing that plan with family members or others who can monitor for symptoms is also recommended.
Symptoms of heat-related illness include heavy sweating or a sudden stop in sweating, rapid heartbeat, confusion, nausea, and loss of consciousness. Anyone experiencing these symptoms is advised to seek medical help immediately. People who take any of the medications on this list and are unsure of their specific risk should speak with their prescribing physician before the heat of midsummer arrives.
