My father in law is 89 y/o, with a pacemaker for a low HR (placed ?4-5 yrs. ago)....absolutely no other health issues. A healthy 89 y/o man who remains active, and is on no meds. Today, he canceled dinner ( his good wife of over 50 yrs of marriage called us.) At the original phone call this morning around 12:30 noontime, his temperature was 99.2F...tonight around 7:00 PM, I called and asked my mother in law How s our patient doing? His temp is now 100F...yes, he did eat a little soup with chicken in it. He s not feeling sick in any way except sleepy and tired. He s been in bed all day. All this is info I obtained from my mother in law. My concern is what is safe temperature for someone this old? My first thoughts are a underlying condition that he might not be aware of. They have not eaten anywhere that he might have food poisoning. He has had one mild episode of shingles, many years ago. He gets the flu vaccine every year. And, yes , he has received Prevnar 13. Would you be watching his temp? And, at what point would you recommend a call to his doctor?