Medications and heat can interact in ways that make extreme temperatures harder for the body to handle. Some widely prescribed drugs, including medications for depression, anxiety, ADHD, high blood pressure and heart conditions, can affect sweating, thirst, blood circulation or the body’s ability to regulate temperature. These effects may increase the risk of dehydration and other heat-related illnesses during periods of extreme heat.
The issue is becoming more important as heatwaves become more frequent and severe. People taking medications that affect thermoregulation or fluid balance may face additional risks when temperatures remain high for extended periods.
Ileana Okumus, a 28-year-old living in Brussels, experienced this during Europe’s June heatwave. Her top-floor apartment reached 34C (93F), and she struggled to cool down after leaving the building. She eventually connected her symptoms with medication she had started taking two years earlier for depression and anxiety.
Her experience highlights a problem that can be difficult to recognize. Heat intolerance is not always caused by temperature alone. Medication, underlying health conditions, housing conditions, access to cooling and exposure to high temperatures can all influence how someone responds to heat.
The U.S. Centers for Disease Control and Prevention has warned that certain medications can affect the body’s response to heat, including drugs that alter sweating, hydration, blood pressure or temperature regulation. The agency’s CDC guidance on medications and heat identifies several commonly prescribed drug classes that may increase heat-related risks.
Mental Health Medications Can Affect the Body’s Cooling System
Several classes of psychiatric medications can influence the body’s response to high temperatures. The mechanisms differ between drugs, but they can involve sweating, thirst, blood-vessel dilation, temperature regulation and a person’s awareness of physical symptoms.
Selective serotonin reuptake inhibitors, known as SSRIs, and serotonin-norepinephrine reuptake inhibitors, or SNRIs, are commonly prescribed for depression and anxiety. Examples include sertraline, fluoxetine, escitalopram and venlafaxine.
These medications can increase sweating. During extreme heat, excessive sweating can contribute to the loss of fluids and electrolytes, particularly when a person cannot replace those losses quickly enough.
The effect can become more significant when high temperatures are sustained. A person who is already losing large amounts of fluid through sweating may become dehydrated without immediately recognizing the extent of the problem.
Tricyclic antidepressants present a different concern. Some can increase sweating, while others can suppress it. Reduced sweating can interfere with the body’s ability to eliminate heat, potentially allowing body temperature to rise.
Many tricyclic antidepressants also have anticholinergic effects. Acetylcholine plays a role in several bodily functions, including sweat production, so medications that interfere with its activity can affect normal cooling mechanisms.
Other psychiatric drugs can also affect heat tolerance. Antipsychotics used to treat conditions such as schizophrenia and bipolar disorder can interfere with normal temperature regulation. Previous heatwave research has associated antipsychotic use with increased risks during periods of extreme heat.
Stimulants used to treat ADHD, including methylphenidate-based medications, can increase heat production and affect blood-vessel behavior. They may also alter how a person perceives exertion, potentially making it harder to recognize that the body is becoming overheated.
The risks can become more complicated when several medications are taken simultaneously.
Caroline Fraissinet, a 36-year-old career coach in Los Angeles, described experiencing increased sweating, irritability and difficulty concentrating during a prolonged humid heatwave while taking an antidepressant, a mood stabilizer and ADHD medication.
She initially attributed the symptoms to diet and insufficient water intake. Later, discussions within her mental health support group helped her recognize that medication could also be contributing to her difficulty coping with the heat.
That possibility is important because people may not associate symptoms such as fatigue, excessive sweating, difficulty concentrating or weakness with medication. They may simply assume that the weather is affecting them more severely than other people.
The CDC information on heat-related illness explains that prolonged exposure to high temperatures can progress from less severe heat-related conditions to potentially life-threatening illness.
Blood Pressure Drugs, Diuretics and Other Medications Add Different Risks
Psychiatric medications are not the only drugs that can make extreme heat more difficult to tolerate.
Diuretics, commonly prescribed for high blood pressure and heart conditions, increase the amount of water and sodium excreted by the body. During hot weather, additional fluid loss through sweating can compound the effects of these medications and increase the risk of dehydration or electrolyte imbalance.
ACE inhibitors and angiotensin II receptor blockers, commonly known as ARBs, are also widely prescribed for cardiovascular conditions. These medications can affect blood pressure and the body’s response to dehydration.
When several medications with overlapping effects are taken together, the risk can become more complicated. A person may simultaneously experience increased fluid loss, reduced blood pressure and impaired ability to compensate for heat.
Beta blockers can create another challenge. They can limit the increase in blood flow to the skin that normally helps the body release heat. This can make it harder for the body to dissipate heat efficiently.
Other medications with anticholinergic properties can also interfere with sweating. These drugs are used for a wide range of conditions, including Parkinson’s disease, overactive bladder, respiratory disorders and allergies.
The risk is particularly important for older adults. People over 65 are already more vulnerable to heat-related illness and are more likely to take several medications simultaneously.
Multiple medications can also create interactions that are difficult for patients to identify on their own. Someone taking a diuretic, a cardiovascular medication and a psychiatric drug may experience several different mechanisms that increase vulnerability to heat at the same time.
The NIOSH heat stress guidance provides additional information about how high temperatures can place physiological stress on the body and why prolonged heat exposure can become dangerous.
The surrounding environment also matters. People who work outdoors, live in poorly ventilated homes or lack access to air conditioning may face substantially greater exposure. Urban heat islands can further increase temperatures in densely developed areas where dark surfaces absorb and retain heat.
During a community health outreach event in Las Vegas, emergency medicine physician assistant Cecilia Ahanonu encountered a man in his 60s who was sleeping in a park during temperatures of about 43C (109F). He was taking a diuretic and an SSRI and appeared pale, with heavy sweating and a high heart rate.
The man initially attributed his symptoms entirely to the extreme heat. Further questioning raised the possibility that his medications were contributing to his vulnerability.
Ahanonu advised him on basic heat-safety measures, including drinking more water and avoiding direct sun during the hottest part of the day. She also directed him toward nearby cooling centers and warned him about symptoms that could indicate heat stroke.
Confusion or an altered mental state is particularly concerning. A person who becomes confused, behaves unusually or has a significant change in mental status during extreme heat may require immediate medical attention.
Better Awareness Can Help Patients Manage Medication and Heat Risks
Doctors caution that people should not stop prescribed medications on their own because temperatures are rising.
The appropriate response depends on the medication, the condition being treated, the person’s health status and the level of heat exposure. A drug that increases heat sensitivity may still be essential for controlling another potentially serious medical condition.
Instead, healthcare professionals can review medication lists with patients before or during periods of extreme heat. That discussion can identify drugs that affect sweating, hydration, blood pressure or temperature regulation.
The need for greater awareness extends beyond patients. Physicians and other healthcare professionals may need to consider heat exposure when prescribing medications to people who are particularly vulnerable to high temperatures.
For patients taking multiple medications, the issue can be especially complicated because several drugs may affect the body’s ability to cool itself through different mechanisms.
The problem is becoming more relevant as climate change increases exposure to extreme heat. Research published in Nature Climate Change has examined the growing frequency and severity of heat stress and the increasing number of people exposed to dangerous temperatures. The study provides broader context for the changing environmental conditions that can amplify medication-related risks. The research on global heat stress and climate change highlights the expanding scale of extreme heat exposure.
For people taking medications that may affect heat tolerance, awareness can make it easier to recognize when symptoms are unusual. Staying hydrated when appropriate, reducing exposure during the hottest periods, using available cooling resources and discussing medication-specific risks with a healthcare professional can all be part of a broader heat-safety plan.
Patients should also be aware that severe symptoms require more than simply moving somewhere cooler. Confusion, altered mental status and other signs of serious heat illness can indicate a medical emergency.
The central issue is not that people taking these medications should automatically discontinue them during hot weather. Rather, medication use is one of several factors that can determine how well the body handles extreme temperatures, making it important for patients and healthcare professionals to recognize the connection before heat exposure becomes dangerous.
