Parents will be told that over-the-counter cough and cold medicines do not work on children under 12, and can even cause side-effects like hallucinations.
A review of remedies such as Lemsip, Day Nurse and Sudafed by the Medicines and Healthcare products Regulatory Agency (MHRA) found "no robust evidence that these medicines work" in children.
The MHRA added that possible side-effects could include sleep disturbance and allergic reactions, and has decided many can no longer be sold for use on children under six. New, clearer advice will be published on packets for children between six and 12. Pain relief preparations and remedies used to lower a child's temperature, such as Calpol, are unaffected by the new rules. For children under six, the MHRA recommends parents stick to simple remedies like keeping their child's temperature down, and honey and lemon mixtures to ease a cough.