Regular hand washing reduces the spread of cold viruses. It is most effective and is especially recommended for use in children, due to a lack of evidence supporting the effectiveness of over-the-counter cold medicines for children, and due to the risk for harm from those medicines. In 2009, Canada restricted the use of over-the-counter cough and cold medication in children six years old and younger due to concerns regarding risks and unproven benefits. The misuse of dextromethorphan (an over-the-counter cough medicine) has led to its ban in a number of countries.