Certain antidepressants can reduce a person’s heat tolerance, making them more prone to heat exhaustion and heat stroke. They should be aware of warning signs like dizziness, weakness, and headache.

According to a 2022 review, two classes of antidepressants — selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) — have physiological effects on the body. They can cause the core body temperature to rise above 106°F (41°C).

People taking these antidepressants should be aware of warning signs of heat stroke, and where possible, they should take steps to regulate their body temperature.

Read on to learn more about the association between antidepressants and heat intolerance, plus safety tips.

According to research, certain antidepressants make people more sensitive to heat. These include SSRIs such as sertraline (Zoloft) and TCAs such as amitriptyline (Elavil). They can make a person more sensitive to heat and cause body temperature to increase above 106°F (41°C).

According to licensed psychologist David Tzall, Psy.D, “SSRIs have anticholinergic properties, which can prevent sweat glands from functioning properly.” Sweating helps the body cool itself naturally, so when it decreases or stops, it can make a person overheat.

“Additionally, some types of antidepressants interfere with actions of the hypothalamus, a structure in the brain involved in heat regulation,” Tzall says. “When the hypothalamus cannot control body temperature, someone can overheat.”

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Research states that several medication classes can contribute to or cause heat sensitivity. Aside from antidepressants, they include:

  • Amphetamines: These are stimulants, such as methylphenidate (Ritalin).
  • Cocaine: This is a recreational drug that can be addictive and harmful.
  • Antipsychotics: These are drugs that treat schizophrenia and other mental conditions, such as chlorpromazine (Thorazine).
  • Diuretics: These are drugs that increase urination to reduce high blood pressure, such as furosemide (Lasix)

Medications may cause heat intolerance in several ways.

As mentioned above, they can suppress sweating and hinder the regulatory action of the hypothalamus. They may also constrict (narrow) the blood vessels, which inhibits cooling. Additionally, some decrease the fluid volume in the body, which reduces blood flow to the skin.

When the body’s temperature-regulatory processes become overwhelmed, overheating can occur. This may cause muscle cramps, fainting, or signs of heat-related conditions.

Heat exhaustion

This happens when excessive sweating causes large losses of water and salt. Signs include:

  • headache
  • dizziness
  • nausea
  • weakness
  • thirst
  • elevated body temperature
  • irritability
  • heavy sweating
  • decreased urine output

Heat stroke

This is the most serious heat-related condition and can result in permanent disability and, in some cases, death. Signs include:

  • excessive sweating or hot, dry skin
  • confusion, slurred speech, or abnormal mental state
  • very high body temperature
  • loss of consciousness
  • seizures

If someone shows signs of heat exhaustion, they need help from others. While waiting on medical help to arrive, the Centers for Disease Control and Prevention (CDC) recommends:

  • removing their unnecessary clothing, including socks and shoes
  • getting them out of the heat and giving them liquids to drink
  • cooling them with cold compresses or helping them wash their neck, face, and hands with cold water
  • encouraging frequent sips of cold water

For heat stroke, while waiting on medical help to arrive, the CDC advises:

  • moving them to a cool area and removing their outer clothing
  • placing cold, wet cloths on their neck, head, armpits, and groin, or soaking their clothing with cold water
  • cooling them quickly with an ice bath, if possible

Heat-management measures can help prevent heat-related conditions. The National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce advocates preparing for high temperatures ahead of time. A person should:

  • Stay current on heat advisories from local TV and radio stations.
  • Plan ahead for heat through:
    • servicing air conditioners
    • obtaining a window fan
    • knowing cool indoor places to go to, such as shopping malls
  • Visit a doctor to see if they have a health condition that hot weather may worsen.

During hot weather, the NOAA recommends:

  • drinking plenty of water and nonalcoholic beverages
  • dressing in lightweight, light-colored clothing
  • avoiding being in the sun for long periods
  • reducing strenuous activity and saving activities — such as gardening or lawn mowing — for early morning or late evening
  • eating light, easy-to-digest foods
  • misting skin with cool water when outside and using cold compresses when inside

The CDC urges prompt medical attention for symptoms of either heat exhaustion or heat stroke. A person with heat exhaustion should get to an emergency room, but if this is unavailable, someone with them should call 911.

If an individual shows signs of heat stroke, people with them should call 911 immediately.

There is a relationship between some antidepressants and heat intolerance. SSRIs and TCAs are medication classes that may cause overheating.

The most concerning heat-related conditions are heat exhaustion and heat stroke. Signs of heat exhaustion include dizziness, weakness, and nausea, while signs of heat stroke include confusion, slurred speech, and hot, dry skin.

People experiencing these symptoms should seek medical attention.