It really heavily depends on what kind of 'sick' it is, and how I actually feel.
Nausea, headache, fever, runny nose, any kind of actual pain? Naw man, that's miserable. Just rest.
But sometimes I feel fine except for a cough or something, and I'll draw anyway because I'm bored. On top of that, I've had several cases of laryngitis in my life, where the only thing that's wrong is I can't speak. Since I can't really hold a conversation while drawing anyway (just me? It's like I can talk or draw, but not both at the same time), it doesn't really stop me.