People who use nicotine replacement therapy are being warned of the harm it can do to children - after a huge rise in calls to the National Poisons Centre and three "serious exposures".

Nicotine gum, lozenges and related products are safe if used by smokers at recommended dosages, but major overdoses can cause symptoms including irregular pulse, breathing difficulties and, in some cases, death.

The Government, through the Quit Group, promotes and subsidises nicotine replacement therapy (NRT) as a quit-smoking aid.

The National Poisons Centre has recorded a steady increase in the number of calls it receives about the exposure of children to NRT, from five in 2004 to 27 in 2009 and 49 last year.

In a report this year to the Ministry of Health, the centre says paediatricians have noticed an increased number of children being exposed to NRT.

"There have been three serious exposures recently in Nelson."

Nelson-Marlborough District Health Board paediatrician Dr Nick Baker said yesterday that three pre-schoolers had been hospitalised with symptoms including nausea, salivation, agitation and vomiting. They recovered.

"Many people carry around a potentially lethal dose of nicotine. We advise that people treat their nicotine replacement therapy as a medicine and keep it out of reach of children."

The poisons centre report says in one case it investigated, the child had ingested 25 pieces of gum.

NRT gum comes in a range of flavours, such as mint, fruit and liquorice. The products' data sheets say it tastes bad if chewed too quickly.

"The risk of poisoning from swallowing the gum is very small, as absorption in the absence of chewing is slow and incomplete," says one brand's data sheet.

The poisons centre says brief skin or oral exposure to used NRT skin patches in children is usually not harmful, causing "few if any symptoms".

Three-quarters of the children about whom calls were made to the centre required medical referral for treatment or monitoring.

"Any more than a minor exposure to pharmaceutical nicotine should be considered potentially toxic in children," poisons centre medical toxicologist Dr Michael Beasley told the Herald.

The ministry's senior adviser on tobacco control, Carl Billington, said that after it was notified of the issue last week, it asked the Quit Group to remind parents to keep NRT, like any medicine, out of children's reach.

The Quit Group said it had sent the new warning to its Quitline advisers and quit-card providers.

Its practice was to tell clients NRT was a medicine, to store in a cool place and to dispose of leftover NRT carefully, away from children and pets.

* Symptoms can include sweating, vomiting, convulsions.

* Lethal dose in children is 1mg per kg of bodyweight - 30mg in a 30kg child, for instance.

* Nicotine gum contains either 2mg or 4mg of nicotine per piece.

* 5 calls to National Poisons Centre in 2004 about children exposed to nicotine replacement therapy.

* 49 calls last year.