Your antidepressant is making summer harder than it needs to be

In this article:

• Antidepressants and heat intolerance
• Comparing antidepressants
• Why they affect body temperature
• Symptoms of heat intolerance
• Alternatives
• Managing your side effects
• When to seek emergency care

In this article

• Antidepressants and heat intolerance
• Comparing antidepressants
• Why they affect body temperature
• Symptoms of heat intolerance
• Alternatives
• Managing your side effects
• When to seek emergency care

Summer heat is hard enough on its own. But if you’re taking an antidepressant, you may find it harder than usual to stay comfortable or safe when temperatures rise. Some antidepressants can cause heat intolerance, an increased sensitivity to heat that goes beyond simply feeling warm. Here’s what you need to know about that risk and how to protect yourself or a loved one taking an antidepressant.

Do antidepressants cause heat intolerance?

Yes, antidepressants can cause heat intolerance. This is a documented, reported side effect, not an uncommon one, and not imagined. If you’ve recently started taking an antidepressant (such as sertraline (Zoloft), escitalopram (Lexapro), or fluoxetine (Prozac) or had your dose increased, that may explain a sudden sensitivity to heat. 

Certain medications can cause heat sensitivity, and antidepressants are among them. Heat sensitivity can emerge when starting a new antidepressant or when the dose is increased. The body is still adapting to shifts in neurotransmitter activity, and that’s often when side effects are most noticeable. 

“When starting or increasing a dose, the body is adapting to changes in neurotransmitter activity,” explains Dr. Jeffrey Chester, DO, medical director of The Ohana Luxury Addiction Treatment Center in Kailua Kona, Hawaii. “During this time, patients are often most vulnerable to side effects, including heat intolerance.”

That’s because neurotransmitters (chemical messengers in the brain that help nerve cells communicate) are involved in the regulation of body temperature. Serotonin, in particular, affects thermoregulation, which is why medications such as selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) can influence how the body responds to heat. 

“While heat intolerance is not a given with these medications, everyone reacts differently,” cautions Dr. Kaitlin Slaven, MD, a psychiatrist with the Eating Recovery Center and Pathlight Mood & Anxiety Center in Bethesda, Maryland. 

Which antidepressants cause heat intolerance?

According to a review of drug-induced hyperthermia in the journal Cureus, two classes of antidepressants are among the medications that can disrupt the body’s ability to regulate temperature. They are: Selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs). 

Serotonin and norepinephrine reuptake inhibitors (SNRIs) are also associated with an impaired or altered ability to sweat, which limits the body’s ability to cool itself effectively. Antidepressants are among the most widely prescribed medications in the U.S., and SSRIs are the most commonly prescribed type of antidepressant.

“These common SSRIs share class effects that can reduce heat tolerance via disrupted thermoregulation and increased sweating, raising risks of dehydration and heat-related illness,” says Jamie Waarbroek, PMHNP, a psychiatric mental health nurse practitioner at Neuro Wellness Spa.

That said, heat intolerance isn’t inevitable. “Most patients can take them safely during the warmer months,” says Dr. Chester. “However, it’s important to pay attention to signs of heat illness and stay well hydrated.”

Here’s what to know if you’re taking one of these three commonly prescribed SSRIs:

Sertraline (Zoloft)

Sertraline (Zoloft) can disrupt the body’s normal cooling process, contributing to heat intolerance in some people who take it. According to the FDA prescribing information for sertraline, hyperhidrosis (excessive sweating) is among the most common adverse reactions, reported at a rate of at least 5% and at least twice that of placebo. Research suggests that a significantly increased risk of hyperhidrosis is associated with most second-generation antidepressants, including both SSRIs and SNRIs, and that dose does not appear to increase the risk. 

Escitalopram (Lexapro)

Escitalopram (Lexapro) is an SSRI with the same class-level risk of heat-related effects as sertraline. According to the FDA prescribing information for Lexapro, increased sweating is among the most commonly reported adverse reactions, occurring at an incidence of at least 5% and at least twice that of placebo. 

Fluoxetine (Prozac)

Fluoxetine (Prozac) is also a popular SSRI prescribed for several conditions, including major depressive disorder (MDD), obsessive-compulsive disorder (OCD), panic disorder, and others. Some people taking fluoxetine may also notice that they’re sweating more. Sweating is also listed as a possible adverse effect in the FDA’s prescribing information for Prozac (fluoxetine). 

Other antidepressants and heat risk

SNRIs carry a similar heat-related risk to SSRIs. Excessive sweating is a possible side effect of this class as well, which can impair the body’s ability to cool itself. Commonly prescribed SNRIs include duloxetine (Cymbalta, Drizalma) and venlafaxine (Effexor).

Tricyclic antidepressants (TCAs) carry a particularly high risk. TCAs are first-generation antidepressants that are now less commonly prescribed for depression, though providers do still prescribe them for other uses. TCAs have strong anticholinergic effects, which can impair the body’s ability to sweat (a critical cooling mechanism). They also cause dry mouth and skin, constipation, and urinary retention.

“Those taking anticholinergic antidepressants are at a particular risk of heat exhaustion or heat stroke,” says Dr. Slaven, adding that they should take precautions and watch for warning signs.

If you’re taking more than one antidepressant, talk to a healthcare provider. The combination can compound heat risk and make it harder for the body to regulate temperature, according to UVA Health.

Common antidepressants and heat-related effects
Generic name	Brand name	Drug class	Heat-related effects noted in prescribing information
Sertraline	Zoloft	SSRI	Can cause possible hyperhidrosis
Escitalopram	Lexapro	SSRI	Increased sweating possible
Fluoxetine	Prozac	SSRI	Can lead to increased sweating

Why do antidepressants affect your body temperature?

SSRIs work by preventing the reuptake of serotonin in the brain. This increases the amount of this neurotransmitter available in the synapses. The hypothalamus is a small structure deep in your brain that maintains your body’s internal systems, such as blood pressure, hunger, and body temperature. This type of medication prevents the reuptake of this important chemical messenger that affects mood, sleep, digestion, sexual desire, and other functions. 

In addition to altering what’s essentially the body’s thermostat, they can also alter the body’s sweating mechanisms, Waarbroek says. “Sertraline and fluoxetine are specifically noted in CDC materials for sweating effects,” she adds. “Escitalopram has been linked in studies to higher heat-related illness rates during heatwaves.”

Some antidepressants can also indirectly contribute to blood vessel constriction. They increase serotonin levels, which tends to make blood vessels narrow. When a drug contributes to the constriction of blood vessels, it can also limit the body’s ability to release heat and cool down. Research on antidepressants and vascular effects suggests this is less likely with SSRIs than with monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants. 

What are the symptoms of heat intolerance on antidepressants?

Heat intolerance is more than feeling warm on a hot day. Someone experiencing it may feel unusually weak or uncomfortable, develop a headache or shortness of breath, or notice heart palpitations. 

Excessive sweating is also worth noting separately. Hyperhidrosis is among the more common adverse effects of SSRIs and can occur even in moderate temperatures. It’s a distinct side effect of the medication, not only a sign of heat exposure.

More serious heat-related illness can develop if early symptoms go unaddressed.

• Heat exhaustion: Signs include heavy sweating, headache, nausea, cool, clammy skin, and muscle cramps. Move to a cool, air-conditioned space, rest, and drink cool water. Notify a healthcare provider, who can advise on whether additional care is needed.
• Heat stroke: Heat stroke is a medical emergency. Call 911 immediately. Signs include a core body temperature above 104°F, hot and dry skin, a rapid pulse, rapid breathing, flushed skin, and a throbbing headache. People with heat stroke may also show altered mental status, such as confusion, slurred speech, agitation, or loss of consciousness. If heat exhaustion is not treated, it can progress to heat stroke.

Are there antidepressants that don’t cause heat intolerance?

Dr. Chester noted that SSRIs, generally speaking, are less likely to cause temperature regulation problems than antidepressants with anticholinergic properties, like tricyclic antidepressants (TCAs). 

So, if you’re taking a tricyclic antidepressant or other first-generation antidepressant, your provider may recommend trying an SSRI or SNRI. If you’re already taking an SSRI or SNRI, then possibly switching to bupropion or another SSRI or SNRI may work better for you. 

“However, the response can vary from person to person,” Dr. Chester said, adding that people should talk to their provider and discuss any other factors that may be contributing and whether or not an alternative may be clinically appropriate.

Waarbroek says that it is acceptable to switch to a different antidepressant if you’re struggling with heat tolerance issues to see if you tolerate it better.

“If heat issues significantly affect safety despite preventive measures, clinicians may switch to another agent with a potentially better side-effect profile, individualized based on psychiatric needs and history,” says Waarbroek, adding that options such as bupropion or other SSRIs/SNRIs might be considered. However, he cautions against sudden medication changes: “Abrupt changes are not recommended.”

A healthcare provider can walk through all relevant factors when choosing the best antidepressant for a given patient, and can guide a gradual taper off the current medication before any transition. For a broader overview of what to expect, see antidepressant side effects explained.

How to manage heat intolerance while taking antidepressants

If you are taking an antidepressant, talk to your healthcare provider to get medical advice about any concerns you have about coping with the heat. Be sure to check about any other medications you’re taking that might have a similar risk.

Here are some additional steps that you can take to reduce your risk of experiencing any danger related to the heat while taking an antidepressant:

• Know your personal heat triggers and pay attention to how your body responds in different conditions. 
• Limit time in the sun during peak hours (10 a.m. to 4 p.m.).
• Wear lightweight, breathable clothing.
• Apply sunscreen to all exposed skin when spending time outside.
• Move to a cool, air-conditioned space if you start to feel uncomfortable. 
• Drink plenty of water to stay hydrated.
• Reduce the amount of alcohol or caffeine that you consume.
• Ask your healthcare provider if you should consider using an electrolyte replacement if you do experience excessive sweating.

“People need to recognize that SSRIs can affect heat tolerance,” says Dr. Chester. “I would also recommend paying close attention to how one’s body responds to heat.”

Don’t adjust your dose or stop taking your antidepressant on your own. If you’re concerned that your antidepressant dose may be too high for you, definitely raise the issue with your healthcare provider before taking any action on your own.

Also, if you have concerns about medication costs, you may want to ask your provider about taking a generic version, as generics tend to be less expensive than their brand-name equivalents. For example, generic sertraline may be better for your budget than the name brand Zoloft. The same goes for escitalopram with Lexapro, and fluoxetine with Prozac, 

When to seek emergency care

Waarbroek encourages people to watch for signs of heat stroke proactively. Don’t wait until symptoms are severe to act. Heat stroke is a medical emergency requiring an immediate call to 911, according to Mayo Clinic. If untreated, it can cause damage to the heart, kidneys, muscles, and brain, and the longer it continues, the more serious the damage can be.

Signs of heat stroke include a body temperature above 104°F, hot and dry skin, a rapid pulse, flushed skin, dizziness, and a throbbing headache. Nausea, vomiting, and altered mental status, such as confusion, agitation, slurred speech, or loss of consciousness, may also occur.

Heat exhaustion is less severe but still serious. Move to a cool space and hydrate. Notify a healthcare provider if symptoms don’t improve. Mild discomfort that resolves quickly after getting out of the heat can be monitored at home.

“Don’t ignore the warning signs, and seek help immediately if you are feeling extremely ill after spending time in the heat,” says Dr. Slaven.

People taking antidepressants may have a reduced ability to perceive their own overheating, making early recognition especially important, particularly during a heat wave. Caregivers and family members should also know the warning signs, since someone experiencing heat stroke may be too confused or disoriented to recognize or communicate their own distress.