Comedian, actor and filmmaker Stephen Fry says his 'astonishing' weight loss of 31 kg came at a price, after a 'fat jab' caused him to throw up to five times a day.

The actor was an early user of Ozempic, an obesity drug, which is currently making news in Hollywood.

Stephen has become the latest big name star to warn of the dangers of the drug after feeling its grim after-effects, according to Mirror, reports dailymail.co.uk.

The star said he was in the US when he read about Ozempic, and asked his doctor about getting a prescription.

Stephen shared that he was pleasantly surprised by the drug's effectiveness and found it stopped all of his cravings for food and alcohol.

The actor said: "The first week or so, I was thinking, 'This is astonishing. Not only do I not want to eat, but I also have no desire for alcohol of any kind. This is going to be brilliant."

“Then I started feeling sick, and I started getting sicker and sicker. I was throwing up four, five times a day and I thought, ‘I can't do this’."

“So that's it. The new variant, Tirzepatide Mounjaro, makes it even worse apparently.”

Stephen was at his heaviest in April 2019. However, by August of that year, he had lost some weight after taking the drug.