By Briar Burley
Legal 'herbal' drugs are sold at many UK festivals
So called legal or herbal highs are often as chemical and dangerous as illegal drugs, doctors have told Newsbeat.
The pills or liquid can be bought online, in shops or at festivals and although they claim to be natural GPs warn they often contain damaging ingredients.
The chances are if you've been to a festival this summer you'll have come across stalls selling herbal highs.
Twenty-five-year-old Alex from Birmingham bought herbal ecstasy with friends at the V Festival last summer.
She said: "We'd been drinking, thought it'd be a good idea - a bit of a laugh.
"There was a stall selling them, so we all thought it was fairly legitimate."
Her and her mates bought one pack each which contained eight pills. They were told to take them all at once. But hours later they all started feeling ill.
"Initially it was really good - you know, we were a bit tingly, a bit happy. A few hours later everyone started feeling really quite poorly.
"I had a really bad upset stomach - there was sickness, diarrhoea and headaches, high temperatures and just generally feeling really quite horrible."
The pills Alex and her mates bought were advertised as herbal - so they assumed they'd be safe. But doctors say that's not always the case.
John Ramsey, a drug expert at St George's Hospital in London, showed Newsbeat some of the legal highs people had brought into the hospital.
"These things are packets of tablets and capsules sold as herbal highs, but are in no way herbal. These things are purely synthetic chemicals," he said.
One of the drugs we've seen is an amphetamine with a chloride compound
Products like this are legal in the UK.
But there's no long-term research into how they could affect your health.
Experts say they're worried about the similarities between some of them and banned drugs.
Dr Paul Dargan, a clinical toxicologist, said: "One of the drugs we've seen is an amphetamine with a chloride compound attached to the side of it, so it's structurally very similar to an amphetamine."
Companies Newsbeat has spoken to said all the ingredients were listed on their packets - which always carried a warning.
But there are calls for tighter controls over the content and sale of legal highs.
One of the main ingredients in many products is the compound BZP.
That's being banned in March although doctors are worried new and potentially dangerous chemicals are being made to replace it.