The Food Safety Authority of Ireland (FSAI) has issued a warning to the public about the dangers associated with consuming cannabis jelly sweets.

The watchdog says a number of items with "significant" levels of THC, the part of the cannabis plant that causes a high, have been seized by Gardaí and Customs officials.

The FSAI knows of at least one incident where a teenager suffered a serious reaction to the sweets and was hospitalised.

The particular sweets were apparently purchased online with the packaging carrying explicit warnings to eat the sweets cautiously and that a significant concentration of THC was present.

THC is a controlled substance in Ireland and in food, the substance is considered a contaminant, with no permitted threshold in the EU.

The Authority is appealing to anyone who comes across the products to notify Gardaí immediately.

Dr Pat O'Mahony, the FSAI's Chief Specialist in Food Science and Technology, said seizures are one known side effect of consuming the sweets, but there are likely to be more.

Speaking to Newstalk, he said: "The warning has been issued because vulnerable people, including teenagers and those with underlying conditions, are purchasing what they think are sweets which are laced with THC, the active component of cannabis.

"In food terms, it's not allowed and it's a toxic chemical basically.

"We are aware of teenagers in a certain part of Ireland who bought these and consumed them, and one of them ended up having seizures and being hospitalised, and the others were hospitalised for observation."

He added that "the problem with any toxicant is when you put it into your body, the effects may not be known".

"In one case we're aware of, the packaging did have a warning to say to just consume one at a time because when you consume cannabis sweets by ingestion with THC, it's a very different metabolism than if you were smoking or vaping," he explained.

"The actual THC doesn't take effect until it reaches further down in the digestion system and by then, there are more side effects and by-products formed.

"The high is achieved apparently but it's not as intense or long-lasting and then you have all the other side effects as well.

"It's really unclear what would happen but based on what we've seen so far, it's certainly not desirable."

'Sinister'

In a statement earlier, Dr Pamela Byrne, Chief Executive of the FSAI, warned that sweets containing cannabis components are being sold online or by other means.

"They are dangerous, particularly for young people and those with prior health conditions who may consume them unwittingly," she said.

"We are warning consumers about the dangers from eating these sweets with cannabis products added.

“This new development is a sinister attempt to sell narcotics in the form of sweets and those involved are obviously not concerned about the consequences of these products getting into the hands of vulnerable people like children who could consume these products unwittingly to the detriment of their health."

Additional reporting by Tom Douglas