A teenager has had to have her colon removed after she consumed illegal diet pills she purchased online in an effort to lose weight before going on vacation with her friends.

The 18-year-old Dubliner developed a life-threatening illness after buying the the herbal slimming agent Botanical Soft Gel on the Internet, according to the Irish Independent.

The teenager was admitted to Beaumont Hospital in Dublin suffering from lower abdominal pain and bloody diarrhoea, five days after she began taking the drug. Doctors diagnosed her with acute ischaemic colitis, a condition brought on by sudden swelling of the large intestine.

Read More: Irish authority warns of dangerous online diet pills this New Year

She then underwent emergency surgery after doctors feared she was in danger of organ failure.

The Irish Medicines Board (IMB) concluded that a high dose of sibutramine was present in the weight loss medicine. The drug is a appetite suppressant, used by people who are overweight.

The drug was banned in Ireland and the US in early 2010, due to the increased risk of heart attacks and strokes.

The IMB believe the drugs came from outside the EU, but have been unable to establish the exact source.

"Because the manufacture of these products is unregulated and does not comply with EU and Irish standards, there is absolutely no way for consumers to know what is actually in the products or what other substances they may contain," an IMB statement said.

"There can be no guarantees as to the safety, quality or effectiveness of these products."

Irish women had part of her colon removed after taking herbal diet pillsGoogle images