The Medicines and Healthcare products Regulatory Agency (MHRA) is warning parents not to give herbal remedy echinacea to children under 12.
The MHRA said the small risk of children having severe allergic reactions to the remedy outweighs its perceived benefits.
The UK drug watchdog described the measure as precautionary and said both older children and adults could continue to use echinacea.
The MHRA said echinacea exposes young children to a greater risk of allergic reactions, including hives, rashes, breathing difficulties and possibly fatal anaphylactic shock.
The head of MHRA’s herbal policy, Richard Woodfield, said: “This is not a serious safety issue, but parents and carers need to be aware that children under 12 could have a low risk of developing allergic reactions.
“The measures being taken are precautionary in nature. Parents should not worry if they have given echinacea to children under 12 in the past.”
Manufacturers of licensed products containing echinacea, some of which are for children, will have to label their products with the warning.