It's an Essential Part of Your Body. It's Also Health TikTokkers' Worst Nightmare. How Did We Get Here?

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Shana used to love training for triathlons. As a nurse working in the ICU of the University of Chicago Medical Center, she'd often finish a night shift at 7 am and then squeeze in a run on the lake before heading to bed.

She even completed the infamous Escape From Alcatraz Triathlon—a 1.5-mile swim from Alcatraz Island to the shoreline, an 18-mile hilly bike ride, and an 8-mile run. She'd had asthma since she was a child, but it rarely interfered with her training, usually only flaring up once a year when she had a cold.

Then her asthma suddenly worsened. One night on the ward, she had a bad attack. She recovered, but had another the next day. And the next. Soon she was nebulizing her medication throughout the day and struggling to walk up stairs. Her doctor put her on heavy doses of steroids to try to calm her lungs.

She finally found relief, but it was short-lived. She gained so much weight from the steroids so rapidly—almost 60 pounds in a month—that she had a hard time moving. “Imagine going to the gym, picking up a barbell, and stacking on 60 pounds of plates, then carrying that around with you all day. In the shower, walking down the street, lying in bed. It was horrible,” she says.

As a nurse, she understood the physiology behind what was happening to her. She knew her throbbing knees and elbows meant fluid was leaking out of her joints. She understood that the pain in her chest was her diaphragm muscle being stretched away from the bone underneath as fluid filled her abdominal wall. And as her face started to swell, she looked in the mirror and recognized the moon face that is a hallmark of Cushing's syndrome, a condition that happens when your body has too much cortisol.

Shana and I met in an online support group. We both have severe asthma, which 8 percent to 10 percent of asthmatics develop: The condition suddenly worsens without a clear reason and stops responding to most medications. Like many patients with severe asthma, we both developed adrenal diseases after having to take huge doses of steroids to manage our frequent attacks. Unlike Shana, I never developed Cushing's syndrome, which is when your cortisol is too high. Instead, I developed adrenal insufficiency, which is when your cortisol is too low. I can no longer make cortisol on my own and must now take a synthetic form called hydrocortisone several times a day.

Fortunately, true disorders of cortisol like Cushing's syndrome and adrenal insufficiency are incredibly rare: According to the Cleveland Clinic, 40–70 people in 1 million have cortisol that is too high and 100–140 people in 1 million have cortisol that is too low. This rarity is why Shana and I, and many members of our support group, are baffled by the “high cortisol” posts flooding social media, and TikTok in particular, which has more than 800 million views of videos tagged #CortisolTok. According to these posts, high cortisol is to blame for a slew of health issues including fatigue, a puffy face, waking up at night, and weight gain (commonly called “cortisol belly”). Many of the influencers posting about cortisol call themselves hormone or weight loss coaches, though they typically don't have medical qualifications.

It's hard to overstate how essential cortisol is to our bodies. Adrenal insufficiency, also known as Addison's disease, was a fatal condition until hydrocortisone was invented in the 1930s. Nowadays, people with adrenal insufficiency have mostly normal lifespans. But it is still a dangerous disease that can quickly flare into an adrenal crisis, which is when your body doesn't have enough cortisol, and your organ systems begin to fail. Some studies show that up to 1 in 4 people die from an adrenal crisis , a tragic reality Shana and I see all too often in our support group.

You wouldn't know that sad truth from the posts that tend to prescribe the standard wellness remedies of the moment: matcha tea, bone broth, celery juice, and cold plunges. Some are even pricier, like a $184 weighted pillow that promises to help you “say goodbye to cortisol” and a $1,000 three-month online “cortisol recovery” program .

Cortisol is a hormone produced by the adrenal glands, two tiny organs, each the size of half a walnut, that sit on top of the kidneys. It regulates our blood pressure, helps us digest food, keeps our blood sugar stable, and controls our circadian rhythm. Cortisol is also critical to our immune system. It repairs tissues and acts as our body's most powerful anti-inflammatory, which is why Shana's doctor gave her such high doses of steroids—synthetic cortisol—to treat her asthma.

Perhaps the biggest danger of this trend is that people are panicking about their cortisol for no reason. Dr. Rachel Pessah-Pollack, an endocrinologist at the NYU School of Medicine, has seen a surge in patients requesting cortisol tests in the past year.

One of her first priorities is to help her patients understand that cortisol not only fluctuates throughout the day, but is different on a day-to-day basis. Our cortisol peaks around 8 am and then falls throughout the rest of the day, increasing in little bumps when we eat, drink coffee, or feel stress. It increases with bad stress like a difficult meeting or a stomach bug, as well as good stress like a family reunion or a birthday party.

“But those bumps are almost always transient and quickly go back to a baseline,” Pessah-Pollack says.

That is why she emphasizes to her patients that cortisol testing needs to be handled and interpreted by specialists. Otherwise, if they use saliva tests at home, as is commonly encouraged on TikTok, they might be unnecessarily spooked when they see their cortisol is all over the map.

Pessah-Pollack is deeply empathetic to her patients' concerns and tries to get to the root cause of why they're worried their cortisol is too high. Many of her patients say it's because they are exhausted or have gained weight. These are two common characteristics of an underactive thyroid, a condition that is thousands of times more common than cortisol disorders, which is why one of her first steps is typically to order blood work to check their thyroid function.

If they're waking up at night, she considers other factors like whether they may have undiagnosed sleep apnea or are drinking alcohol shortly before bedtime. And if they're worried about weight gain, she helps them analyze their activity level and how their exercise and nutrition needs may be changing with age. Unless she sees the telltale signs of Cushing's, like stretchmarks on a patient's thighs and stomach, central obesity, high blood pressure, and high blood sugar, she doesn't worry that their cortisol is too high.

So, how does cortisol get so misunderstood?

Cortisol took off as a buzzword associated with stress after the publication of naturopath James Lee Wilson's 2001 book, Adrenal Fatigue: The 21st ^Century Stress Syndrome . In the book, Wilson argued chronic stress damages the adrenal glands, which means a lot of people don't have enough cortisol and feel exhausted and foggy as a result. He coined this condition “adrenal fatigue,” and although it is not a recognized medical diagnosis, it became popular in wellness communities.

For years, Google search trends show about equal interest in low and high cortisol. Then, in 2022, searches for “high cortisol” skyrocketed. Around that time, several studies came out linking stress about the COVID-19 pandemic with increased levels of cortisol in health care workers and the general population. Perhaps this contributed to the sudden spike of interest in high cortisol.