Demi Lovato has come under fire for promoting a "fat-burning" detox tea which contains a risky laxative with potentially dangerous side effects.
The singer posted a photo on Instagram on last week, posing with a bottle of Teami tea, and urging fans to join the firm's 30-day detox programme, reports Daily Mail.
"This year is all about #selflove," Lovato wrote.
However, fans were quick to point out that the anti-bloating, metabolism-boosting blend, Teami Colon, contains senna leaf, a laxative singled out by health officials as a potent herb that irritates the colon and removes important nutrients from the bowels.
Fans also accused the 24-year-old of mixed messages, by promoting a healthy body image while peddling an unregulated weight loss product.
Senna leaf is an FDA-approved laxative to treat constipation, or to clear the bowels before a colonoscopy.
But various medical boards have warned against using the herb for a prolonged period of time, including the National Institute of Diabetes and Digestive and Kidney Diseases, the American Herbal Products Association, and the American Cancer Society.
They warn senna's active components, the chemicals glycosides and sennosides, irritate the lining of the colon, causing muscle contractions.
For people with chronic constipation or irritable bowel syndrome, the product can help to retain fluid in the gut, soften stool and stimulate bowels movement.
However, this stimulates a process that may not be ideal for otherwise healthy people looking for a boost.
As the herb stimulates the bowels, it can trigger gas, bloating, cramping and diarrhoea.
Women are told to avoid senna leaf throughout pregnancy and their nursing period.
Physicians also warn against drinking the herb if you have experienced extensive bloating, abdominal pain or bowel issues.
Lovato is hardly the first celebrity to promote a detox tea.
Other brands to have used senna include Slendertoxtea and SkinnyMint, which is endorsed by Kylie Jenner.
In answer to the question "Does the Teami Colon create a laxative effect?", Teami writes:
"You may experience slight cramping and frequent visits to the bathroom due to the laxative effect. Your body is trying to detox all of the stored toxins in the colon and kidneys. This should NOT include diarrhoea, dizziness, vomiting or severe cramping.
If you experience any of these try to adjust the strength of the colon cleanse tea bags by soaking the tea bag for less time (Example - steep for 1-2 minutes then remove from the mug). If this doesn't reduce the effects then you may need to stop using the tea and consult your general practitioner."