Should my friend worried about mercury poisoning?

My friend broke a thermometer for measuring his fever and the mercury spread all over. He already cleaned it and opened the windows and everything. Some of the mercury got on his hand when the thermometer brakes. My question is what kind of mercury are usually in thermometers? and how much? because I don't know if this will be a serious problem for him. I don't know if that little amount can cause serious health problems. It got on his hand but he said it dissappear, I don't know if it is obsorbe, he didn't ingest any of it. Is this dangerous? should he go to the doctor for this? I just don't know if this is alot of mercury involve or not for it to be serious. Thanks alot for your help!!