How to Describe It
Whether you know a child who has just been diagnosed with OCD, or a child who knows someone who has just received the diagnosis, it can be scary and confusing for them. Describing the disease in a way that they can relate to can take away some of the fear they might feel, and can also help to clarify any misconceptions they might have. But you might wonder, "How do I explain OCD to a kid?" Metaphorical descriptions can help.
If someone else has OCD, you can compare the disease to hiccups, in that it can't be controlled, and can come without warning. Make sure that kids understand that the person isn't truly trying to be difficult, and that OCD is not the person's identity. It's just an issue that the person has that must be dealt with.
Externalizing the concept of OCD is important. If a child has been diagnosed with OCD, try to give the disorder an identity. You might want to ask the child to draw a picture of it, to give it a name, and to even talk in a different voice to personify it. For example, the kid might draw a picture of a scary monster, or of a "mean guy." This can help the child with OCD recognize that the OCD is the enemy, but that they are not the enemy. In this way, when you discuss different tactics the child can use to "defeat" OCD, he or she can view it as a battle against an enemy rather than trying to change an intrinsic part of themselves.