Red Rash Is Raw in Groin

Could be chafing. It's unlikely to be an allergy to the antibiotic if it's only in that one spot. However, amoxicillin or any antibiotic can result in an imbalance - killing off bacteria (including beneficial ones) can allow yeast to grow. We think of vaginal yeast infections after antibiotic use, but yeast can grow in any moist environment, including the folds of the groin. A lot of babies get it and it looks like diaper rash, but isn't. So, don't use any powder in that area, try to keep it dry especially after a shower, and try an anti-yeast cream (ask the pharmacist).

Sounds a little like chaffing.
When my husband gets that he puts some vaseline on it so it doesn't rub as much.

If sweat and moisture is a problem then once it's cleared up consider using an antiperspirant in those areas.
It comes in handy in other places besides arm pits.

https://www.sweathelp.org/hyperhidrosis-treatments/antipe...

That happens to me sometimes too. Very annoying. I will use butt paste. It was the only think I could use for my youngest sons diaper rashes when he was little and found it works for so may other things.

pink salve or maybe some aloe.

How is amoxicillin or bactrim related to skin in the fold between tummy and leg looking red as if it was rubbed? This is not a condition that requires an urgent doctor visit.

Another possibility for increased irritation is the elastic in your panties.

Try vaseline or a dusting of corn starch before going to the doctor. If you're anxious about this, call the advice nurse. You can make that call even tho you're out of town.

K.

you need to take a benadryl. if the rash goes away with that? You know it's an allergic reaction to Amoxicillin.

You need to inform your pharmacist and doctor of the reaction.