The agency said it had received two adverse event reports relating to aconite, one with kidney problems and another with dizziness and paresthesia.
MHRA classifies aconite as an, “extremely poisonous plant that is toxic to the heart.”
“Herbal products containing this ingredient could be fatal or cause serious illness if consumed,” MHRA said.
Aconite, also known as monkshood, is safely used in homeopathic medicines that are controlled in strict doses under medicines law, but is outlawed for use in food supplements such as botanicals.
MHRA head of herbal policy, Richard Woodfield, emphasised the botanical/homeopathic divide.
“Registered homeopathic products that contain aconite are considered acceptably safe as the active ingredient, aconite, is sufficiently diluted,” he said.
“Herbal medicines are made from plants and so can have a very significant effect on the body. In certain cases, such as with aconite, the medicine can be extremely potent. This is a classic case where ‘natural’ does not mean ‘safe’.”
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But Woodfield said such use did not mean product quality could be assured, but he highlighted improving standards.
“With unlicensed herbal medicines, people need to be aware that the standards vary widely and can be poor,” he said. “However, an increasing range of herbal medicines made to assured standards are available on the UK market.”
He noted that registered and licensed herbal medicines can be identified by the Traditional Herbal Product Registration or the product licence number on the label.