Final answer:
To purchase cough medications with dextromethorphan, one must be at least 18 years old. The effectiveness of such medications is questionable, especially in children.
Step-by-step explanation:
In order to purchase over-the-counter cough medications containing dextromethorphan, a person must be at least 18 years old. Dextromethorphan, commonly abbreviated as DXM and sometimes referred to as robo, is a cough suppressant used in various OTC cold and cough medications. These medications are sometimes abused by adolescents and young adults.
It is important to note that the efficacy of cough medication, particularly in children, has been questioned. A 2014 Cochrane review suggested lacking evidence for or against the effectiveness of OTC medicines in treating acute coughs. Moreover, the effectiveness of DXM in decreasing coughs has mainly been noted in adults with viral upper respiratory infections, but not found to be effective for children.