I always weigh this when I'm sick, because I have three related factors that make fevers much more difficult for me (30F).

I have MS, and that means:

• One of my particular brain lesions is in my hypothalamus, which affects my body temperature and my perception of it.
• My body temp going over about 37.5°C/99.5°F starts to make my other, previous symptoms come back/be worse, including dizziness, balance, and leg weakness. When I had a fever with COVID, I was literally clutching walls, back of chair, etc. to get from room to room. (Normally I don't have any walking issues, only when I'm too hot.)
• I almost never sweat. It will occasionally kick in, with maybe 20% of the sweat I should/used to be able to produce. So I can't bring my body temp down without external help like water/ice or cold air. If I don't have access to these, I'm at risk for heat stroke.

Thankfully, I don't get fevers often, but when I do, they seriously kick my butt. My first dose of COVID vaccine took me 3 days to feel mostly normal and a full week to feel completely normal. I have had 4 doses now, and know to proactively take both naproxen and acetaminophen at their recommended highest dose/interval.