A New Zealand company has hit back at claims its caffeine-laced energy strips could lead to addiction, kidney failure and stroke.
Reddies Energy Strips are pitched at students, nightshift workers and athletes with the slogan "recharge smarter".
The dissolving strips - which each contain 40mg of caffeine, about the same as a can of cola - are available in New Zealand and Australia for about $5 for a packet of five.
Doctors in Australia are concerned about the availability of caffeine products which can lead to dependence, increased heart rate and blood pressure and thickening of blood vessels which may cause stroke.
One expert warned they could be especially dangerous for children who cannot metabolise caffeine as effectively as adults.
However, the company said it made a "conscious decision" to ensure its marketing did not appeal to children, and the product's comparatively low level of caffeine made the strips healthier than energy drinks, which also contain high amounts of sugar.
"I'm not saying the concerns aren't valid, but I think it's got to be taken in the context of the marketplace and in the behaviour of the promotion of the products," Reddies co-founder John Nolan-Neylan said.
"Anyone that looks at the way that we package it would accept that it is less appealing than existing products to children, and that's been a conscious decision of ours."
The packs warn the strips are "not recommended for children, pregnant or lactating women, or those sensitive to caffeine".
Mr Nolan-Neylan, who said he usually takes one or two a day, also defended the health impacts of the product, saying small amounts of caffeine boosted mental performance and energy.
Dr Craig Thornley, principal advisor of public health for the Ministry of Primary Industries, said people should be careful about how much caffeine they consume and watch out for side effects, such as anxiety, or inability to sleep, which can appear after taking 210mg a day.
"If you're consuming these strips ... in addition to other forms of caffeine, then you may be pushing your intake to a level that you start experiencing some adverse effects," he said.
"These sorts of products are not for children or young people, and parents and caregivers should be aware that children and young people are more vulnerable to the adverse effects of caffeine and be particularly careful about providing them with caffeine-containing foods or other items because of the potential for harm."
The ministry had received no complaints about the product, Dr Thornley said.
• Each strip contains 40mg of caffeine, about the same as a can of cola or cup of tea.
• One packet contains five strips, a total roughly the same as a double espresso.
• A caffeine intake exceeding 400-500mg a day is considered dangerous for adults. Between 5-10g is considered a fatal dose.
• About 90 per cent of New Zealanders aged over 15 consume caffeine in some form.
• The mean intake of children aged 5-12 is 20mg a day.
• The mean intake of adults aged 31- 50 is 614 mg a day.