I had my tonsils out when I was 25 because I had been getting strep/tonsillitis recurring about every two weeks, and apparently I was mildly contagious to everyone all the time.
Having tonsils out as an adult.... brutal.
My throat looked like a Jackson Pollock painting.
The recovery time was eight full weeks.
Dehydration is the biggest risk because you will do literally anything to resist swallowing.
The immune system goes haywire at first, immediately giving you nasal congestion that tries to make you into a mouth-breather through your scabbed-over throat, and this is the most horrible pain you can imagine, in spite of heavy opioids.
(I know all about pain. I've had kidney stones also. Trust me, we're talking really bad pain.)
I actually started duct taping my mouth closed at night to prevent myself from mouth-breathing because I would wake up after having slept for like an hour in so much pain. I kinda knew that this was probably not safe, but I decided I'd rather die than fall asleep with my mouth open. Fortunately I survived.
I don't regret having it done, but this is something you want to do only if you REALLY can't live with things the way they are.
Edit: Here's one extra detail. I really tried to hydrate and to eat soft, high-calorie foods. I'm six feet tall, average build, but after two months of recovery, I weighed 110 lbs.