from journal BMJ
Children commonly have six to eight colds per year, usually caused by viruses. Usually, symptoms of a cold will clear in a few days. A study in the journal BMJ Today cautions against giving children under the age of six decongestants because there is no evidence they alleviate symptoms such as a blocked or runny nose. Authors say safety of such over-the-counter medications in young children is unclear and in children under age two, decongestants containing antihistamines have been associated with serious consequences. The study suggests that for adults decongestants alone or with antihistamines or analgesics can have a small effect on nasal symptoms. But side effects can include insomnia, daytime drowsiness, headache or stomach upset.