On Facebook, the post in question was originally shared in June 2022. In under 24 hours (as of July 31 2023), the post was shared more than 11,000 additional times.
Neither linked variation provided a source for claims on the graphic. On it, white text against a red background asserted:
Anti-depressants during hot weather
If you are taking sertraline, citalopram, duloxetine, fluoxetin, mirtazipine OR any other SNRI/SSRI you are more prone to overheating and dehydration
Please stay safe in this heat! stay in the shade, stay hydrated, and wear sun cream
On July 28 2023, Associated Press reported that “nearly 200 million people in the United States, or 60% of the U.S. population, [remained] under a heat advisory or flood warning or watch” since July 27 2023 — one likely reason the graphic was recirculating. A July 18 2023 Reuters.com article, “Intensifying heat waves prompt health warnings for Europe, US,” indicated that the European Union’s emergency response coordination center had issued high temperature red alerts “for most of Italy, northeastern Spain, Croatia, Serbia, southern Bosnia and Herzegovina, and Montenegro,” adding:
The European Union’s Copernicus Climate Change Service says 2022 and 2021 were the continent’s hottest summers on record. Europe’s highest recorded temperature of 48.8C (120F) was registered in Sicily two years ago [in 2021].
Scientists have long warned that climate change, caused by greenhouse gas emissions mainly from burning fossil fuels, will make heat waves more frequent, severe and deadly. They say governments need to take drastically reduce emissions to prevent climate catastrophe.
Heat waves this summer [of 2023], which saw temperatures climb to 128F (53C) in California’s Death Valley and over 52C (126F) in China’s northwest, have coincided with wildfires from Greece to the Swiss Alps and deadly flooding in India and South Korea.
They have added renewed urgency to talks [in July 2023] between the United States and China, the world’s top greenhouse gas polluters.
TinEye’s reverse image search returned seven results in total. It was first crawled on July 20 2022 via Twitter, but only a direct link to the image functioned properly. A Google Lens image search returned a Twitter iteration published on July 19 2022:
In June 2020 the Washington Post published “Risks for some medications rise as temperatures climb,” an article that was behind a paywall, potentially hiding it from visitors attempting to validate the meme. It addressed several classes of medication (including antidepressants), and reported in part:
… if you are among the millions of Americans taking certain medications, you may be facing an additional risk [during extreme heat]. Some drugs, taken when it’s hot, can provoke serious, sometimes life-threatening reactions.
These include drugs widely used for many common conditions, including blood pressure, asthma, depression and allergies, among others. When the temperature rises, they can impair the body’s ability to cope with heat.
Some medicines, such as diuretics, make our bodies lose water, which can result in dehydration when it’s hot outside. Others — such as beta blockers or ACE inhibitors — lower blood pressure, which makes fainting more likely in the heat. Selective serotonin reuptake inhibitors — commonly prescribed antidepressants like Prozac — can make us sweat more, also causing dehydration.
Still others — the OTC allergy drug Benadryl, for example, Cogentin, a medication for Parkinson’s disease, and Spiriva, an asthma treatment — can reduce sweating, the body’s natural cooling mechanism, which can lead to overheating and heat stroke. Finally, others — antipsychotics, for example — can hamper the brain’s ability to regulate body temperature.
On July 29 2022, CBC.ca assessed the circulating antidepressant heat wave warning in an article — deeming the risk “pretty minimal,” and referencing several classes of medication:
Social media posts, like the one shown below [the red image], provide warnings that certain medications can interfere with the body’s ability to regulate temperature. These posts are true to an extent, says Mark Yarema, medical director of Alberta Health Services’ Poison and Drug Information Service, but the contribution of medication to most heat illnesses is “pretty minimal.”
Yarema said one of the best things people can do is simply be aware if they’re taking medication that might affect them during a heat wave. He groups those medications into two categories.
Some have a direct effect on the body. For example, some antidepressants, anti-psychotic medications and allergy medications, like Benadryl, can interfere with the ability to sweat properly, while some blood pressure medications are diuretics, causing fluid loss and leading to a slightly higher risk of dehydration.
Medications in the second category have what Yarema calls an “indirect effect” during hot weather. This includes some antidepressants and anti-psychotics, but it’s more likely sedatives like sleeping pills or anxiety medication.
An August 13 2022 BBC.com item (“Some antidepressants may make heatwave challenging”) didn’t mention the then-circulating social media warning, and mentioned the absence of “more conclusive evidence”:
Dr Wendy Burn warns people should not suddenly stop taking their medication, and should seek advice … Dr Laurence Wainwright, a researcher at the University of Oxford’s psychiatry department, told the BBC there is “evidence to suggest a link between tricyclic antidepressants, antipsychotics and heat-related illnesses”.
Dr Wainwright says there is also some early evidence to suggest that SSRIs “may present implications for the body’s ability to thermo-regulate and in turn have other implications for heat-related illnesses”.
He adds “it’s hard to make clear statements here – but there is a complex interplay between serotonin and thermo-regulation”.
It is not known how many people are likely to experience heat-related side-effects. But with more people reporting changes in how they feel during extremely hot weather, it could lead to more conclusive evidence.
On August 14 2022, British tabloid Express.co.uk addressed the topic (without linking the image) in “Antidepressants that become ‘incredibly dangerous’ in the heat – expert’s warning.” A WebMD entry (“Do You Take Medications? Watch Out for Summer Heat and Sun”) addressed the issue broadly, once again describing common medications in several classes:
… Diuretics are an example [of drugs that increase the risk of dehydration]: They are designed to remove water from your body. But when you sweat, you also lose water, leading to dehydration. Examples of diuretics are chlorothiazide (Diuril), furosemide (Lasix), and spironolactone (Aldactone, Carospir).
Selective serotonin reuptake inhibitors (SSRIs), which are common antidepressants, can make you sweat more. This can contribute to dehydration. Examples include fluoxetine (Prozac) and sertraline (Zoloft).
Lithium, a mood stabilizer, is a salt that becomes more concentrated in the body when people sweat. High concentrations can intensify the medication too much, leading to lithium toxicity or confusion, slurred speech, and tremors.
Some medications prevent sweating.
“Sweating is the body’s cooling mechanism, so when people can’t sweat, there’s a danger that they can become overheated, resulting in heatstroke,” says [Barbara Bawer, MD, a primary care doctor at the Westerville Primary Care Office in Ohio].
Medications that prevent sweating include antihistamines like diphenhydramine (Benadryl), and anticholinergics, which are prescribed for many conditions, including asthma, chronic obstructive pulmonary disease (COPD), overactive bladder, and Parkinson’s disease.
Blood pressure medications also raise the risk of overheating …
Side effects of SSRI’s can include hyperhydrosis, they are anticholinergic (can reduce thermal regulation) and increase heat sensitivity. All of these can lead to being more susceptible to dehydration and heat damage. Sources: Canadian gov’t published warnings for heat waves, Consumer report on SSRI …
An appended link led to a July 27 2022 syndicated fact check of the image by Verify.com, “Yes, people who take antidepressants can be more vulnerable to the heat.” In it, a psychiatrist described heat and antidepressant interaction as “not common in most patients,” and said “under ten percent” of patients were likely to be affected by heat waves:
[Psychiatrist Dr. Andrew] Farah says antidepressants are the second most commonly prescribed medications worldwide and people take them for a variety of reasons. He says they can make you more sensitive to heat but it’s not common in most patients.
“It does exist on a spectrum some people are so mild that they don’t notice it and some people find it very troubling but again we’re not talking about huge numbers,” Farah said.
So what are those numbers? Farah says under 10 percent. He says some of the medications to look out for are newer ones like citalopram or duloxetine.
As heat waves raged in the United States and Europe in July 2023, a warning about “antidepressants during hot weather” circulated on social media. We were unable to identify the graphic’s originator, and it was first crawled on Twitter in July 2022. Several articles were prompted by the viral warning; quoted medical experts explained that the risk was mild and rivaled by the risk that patients might cease taking their medication for fear of increasing the risks of heat-related illness. In a 2022 fact check, one psychiatrist estimated that “under ten percent” of patients were likely to be affected.