It is common for a dry cough to linger after a cold, even for several weeks. One way to help alleviate this is to encourage your child to drink plenty of fluids. Sometimes, nasal drip can lead to a cough, so using a saline solution such as Hydrasense for sinus hygiene can help. This product can be used multiple times throughout the day and may help reduce the cough over time. It's important to be patient, as gradual improvement is expected. If you have any further questions, feel free to ask!