The appeal of detox tea is straightforward and endlessly promising: drink me and be thin. You don’t have to look very far to see detox tea companies equating thinness to health, and then turning around and selling you a thinner version of yourself in the convenient form of a celebrity-endorsed Instagram post and a few dedicated swigs of tea. The sales model is one that detox tea giants like Skinny Mint, SkinnyMe, Flat Tummy Tea, Slendertoxtea, Bootea, and Skinny Teatox have capitalized on. With promises of weight loss often directly in the company names, it’s clear that “detoxing” has become a convenient euphemism for what these teams really are: glorified, and potentially harmful, weight loss supplements.

The do-nothing-and-be-rewarded mentality is reminiscent of sketchy diet pills like Hydroxycut and Lipozin, only this time the message has been diluted through a seemingly innocuous substance. Tea is synonymous with comfort. It is safe and familiar. There is no way it could ever hurt anyone more than the possibility of a burnt tongue. Now that it also promises the benefit of effortless weight loss, it’s only natural we would want to try a cup.

But when it comes to detoxification, Stella Metsovas, a gut health specialist and California-based certified clinical nutritionist, is quick to warn against placing too much faith in something marketing itself as a quick fix: “The golden rule of creating a healthy digestive tract is to never rely on a product for the relief of ailments like constipation, or that believing a supplement is going to detox your gut from harmful bacteria — they should always be considered as ‘in addition to’ a healthy diet,” Metsovas tells Teen Vogue. “Nothing will magically detox your digestive tract — which includes your colon — unless your diet has a large percentage of plant-based fibers.”

Yet the magical promise of weight loss and detoxification through tea seems to be working: to date, the #teatox hashtag alone has spawned over 300,000 Instagram posts. And celebrities likeKylie Jenner, Vanessa Hudgens, and Lindsey Lohan have all posted pictures endorsing various brands. Despite there being no hard evidence backing the claims made by tea companies that detox teas cleanse human cells, the industry has, by all accounts, flourished.

Beyond the inspirational Instagram posts and glamorous celebrity endorsements, the hype behind detox tea doesn’t quite add up: how can tea alone make you lose weight? The answer, it turns out, is that it can’t. At least not in any way you want to experience.

Detox tea programs usually come in two parts: a daytime tea, and a nighttime one. The daytime tea is riddled with caffeine from blends of yerba mate, guarana, and green tea. Caffeine is known to have a diuretic effect. While some studies have shown a link between caffeine consumption and weight loss, others have also gone on to find a link between caffeine consumption and weight gain, leaving the evidence for weight loss from caffeine consumption in the dark. But daytime teas don’t stop at caffeine: some also contain a dandelion root, another known diuretic. “The weight loss [from detox teas] is primarily, and probably all, water weight,” Dr. Karin Kratina, a nationally recognized nutrition therapist, tells Teen Vogue. “If true weight loss occurs, it is because a caloric deficit also occurred from a change in eating habits.”

The nighttime tea — billed as the “cleansing and detoxification tea” — is where the real weight loss, or “detoxification,” happens. This is largely due to senna root and leaf. Senna is an FDA-approved laxative used to treat constipation and clear the bowels of patients pre-colonoscopy. It works by irritating the colon to empty its contents and is known as a “stimulant” laxative. Basically, ingesting senna is going to make you have to go to the bathroom… a lot. And afterwards, you’re going to feel lighter because you have successfully emptied out the entire contents of your intestines. While pooping out a pound or two might seem like an activity that’s innocent enough, the laxative process isn’t usually quick or painless. As ridiculous as it sounds, trips to the bathroom can take hours to complete after senna use. It’s why you’ll find warnings like“ensure you have ready access to a toilet during the day until you know how your body reacts to the tea" on nighttime detox teas.

During this window — and let’s call it a window for lack of a better word — users are likely to experience cramps, stomach discomfort, and diarrhea. The U.S. National Library of Medicine claims these are expected side effects of senna, but they also state: “Don't use senna for more than two weeks. Longer use can cause the bowels to stop functioning normally and might cause dependence on laxatives. Long-term use can also change the amount or balance of some chemicals in the blood (electrolytes) that can cause heart function disorders, muscle weakness, liver damage, and other harmful effects.”

While prolonged use of senna can weaken the colon and lead to dependence on the drug, it doesn’t hurt detox tea companies. Turns out, dependence is great for business: if detox tea users find they can’t properly function without the tea, they are more likely to turn into repeat customers.

Not using senna for longer than a maximum of two weeks and not including it as part of a long-term plan can help prevent these unwanted side effects. Yet many detox tea programs involving the herb come in packages of 28-day plans. These 28-day programs instruct users to only consume senna every second day, but the maximum recommended a dosage of a drug intended to treat patients pre-colonoscopy. That's like taking the maximum daily dosage of extra-strength Tylenol for a paper cut on your thumb. It doesn’t make any sense, nor is it good for your health, and it certainly won't help you shed pounds in the long run.

As if consuming the maximum dosage of senna weren’t enough, teatoxes are also branded as “movements” to join indefinitely instead of one-time cleanses. “Join the movement and start feeling Boo-Tea-Ful,” writes Bootea on their website. With the movement mentality these companies promote, it’s easy to see how teatox companies provide ample encouragement for prolonged and repeated senna use, and end up walking dangerously close to the line of maximum recommended dosage, if they don’t cross over entirely.

Yet with all the known potential dangerous side effects of senna, detox tea programs often come with little or no warning label, leaving many users to discover the dangers on their own:

“The only warning my teatox had was that different people might have different reactions,” Billie Schwab Dunn , a 21-year-old blogger in Sydney, Australia who tried one of the teas a year and a half ago with two friends, tells Teen Vogue. “There weren’t any proper warning labels or anything like that. I’m just surprised that something like that can be on the market without fair warning about how your body could react.”

Billie and her friends were interested in trying one of the popular detoxes after seeing Instagram users posting endlessly positive reviews about the program: “It seemed like there were so many people who had so many good experiences with it. It came across as this super-easy drinking tea that would make you feel so much healthier and better and be skinny,” she says. Bille felt fine after drinking the daytime tea, but after drinking the nighttime tea she found her experience not going as planned: “I woke up at midnight with the worst cramps imaginable. It was a shock for it to be happening. I’ve never felt cramps like that ever. I was struggling to walk.” Having seen only positive reviews for the tea, Billie tried the nighttime tea twice more, deciding to write her first experience off as a one-off fluke. “But I got horrible cramps every time I used it, and the same thing happened to the two of my friends.”

Sarah Lawrence*, an 18-year-old student from Calabasas, California, also tried a teatox program after seeing positive results on Instagram. Sarah chose to go with Bootea, and couldn’t wait to see results: “I had just come back from my first semester of college and really wanted to reset my body after having gained a few pounds during my first semester away. I ordered the 28-day Bootea cleanse and was really excited to try it. But the first night after taking the nighttime tea I got this splitting pain in my stomach at 3 a.m. It was one of the most horrible things I have ever felt — we’re talking about a gut-wrenching pain. It was kind of scary because I didn’t know what was happening, all I knew was that I had drank the tea.” After ordering nearly a month’s worth of tea, Sarah decided to try sticking with the program for a little longer: “I couldn’t change the fact that I had already paid for all this tea. Plus the nighttime cramps had eased off and by about two weeks I had already lost five pounds. It was around that point that I was supposed to get my period, but it didn’t come. My period is pretty regular so I started to worry when another week had gone by and it still hadn’t shown up.”

Sarah took a pregnancy test, which came back negative. After noticing she had begun to feel sluggish and dizzy on a regular basis, she decided to stop drinking Bootea before her detox was up. “I gained all the weight I had lost back basically as soon as I stopped drinking the tea. But I started to feel normal again and I got my period soon after that.”

Jenny, a 22 year-old fitness blogger from Luxembourg, also found detox tea interfered with her menstrual cycle: “After 2 weeks I had a super flat belly and I lost 4kg, but NOT because of this Teatox but because I couldn't eat anything anymore,” she documented on her blog Lifting Fairy. “I constantly had bellyaches and diarrhea. I didn't feel good at all and In addition to the bellyaches I also had many headaches and my whole body felt bad. But worst of all, my menstrual cycle became totally irregular. Which I think shouldn't be happening while doing a detox program?! I mean how can a tea to influence your menstrual cycle? This Bootea seems to contain some really weird ingredients and I'm not sure yet if I want to know what I exactly consumed these 14 days.”

The scientific reason behind detox teas causing irregular periods is unclear, but Sarah and Jenny aren’t alone. Several online women’s health forums and teatox reviews show other women documenting the same thing. Dr Kratina says that the reasons behind period disruption from detox tea are not clear, but explains stimulants found in detox teas can affect stress hormones, and that stress hormones are known to affect the menstrual cycle: “The stimulants in detox tea could tax the body, causing more cortisol and adrenaline, the 'fight or flight' stress hormones,” Dr. Kratina tells Teen Vogue. “Sex hormones can take a back seat to stress hormones when the body is going through a difficulty.” (It should also be noted that detox teas have the ability to seriously mess with your birth control, and most companies place such warnings on their boxes.)

It’s important to note that not everyone who has completed a teatox has reported these negative effects. Many users continue to praise teatox programs as jumpstarts to health and wellbeing. Yet the amount of people who have spoken out about the negative side effects they were not made aware of before embarking on their tea detox is enough to warrant comment from these companies.

When asked about how their tea is making some users sick Skinny Mint, Flat Tummy Tea, Slendertoxtea, and Bootea all declined to comment. Skinny Teatox replied with an email statement that claimed the safety and health of their customers is paramount to them, and that the company highly discourages long-term detox tea use and “recommends waiting several months before a new period is started.” When asked where this recommended waiting period can be found, Skinny Teatox failed to reply, but it doesn't matter, tea (or any diet for that matter) shouldn't delay your menstrual cycle.

It's fine to want to increase your strength by working out, or to try to make an effort to eat more whole grains and fresh vegetables in a bid to get healthier, but you should never put your health at risk for the chance to lose a few pounds quickly. It's just not worth it.