That's exactly what I use them for, and they've been brilliant. Usually some advice on what to do next, or when to begin worrying, and, a couple of times, an ambulance - once for very severe dehydration due to diarrhoea and vomiting that led to a hospital stay of a few days, so the ambulance was needed. Recently, I got probably-norovirus and wasn't keeping water down for >24 hours, and they were great for telling me what signs to look for so I didn't get fally-over poorly again. No ambulance that time, just good advice. Sadly, all stuff I did already know, but medical knowledge goes out of the window when it's you that's poorly.