You should listen to this vet unless you want to (& can afford) a second vet opinion. This vet's guess may be right, but it may not- I'm a very experienced snake keeper but not a vet, & I don't play one on here.None of us are seeing your snake in person either, so keep that in mind. This forum cannot take the place of a real vet, & should not be expected to do so.
But -IF there is no testing done to see what antibiotic WILL be effective against the issue at hand, it can totally miss the target (be ineffective) & yes, antibiotics have a bit of a downside too. They destroy both bad AND good bacteria- including the snake's good gut bacteria essential for digestion, which is why we recommend giving probiotics -only those made FOR snakes (& there's several on the market)- following antibiotic therapy.
It's not that unusual for vets to take an educated guess as to which antibiotic to use, in lieu of doing expensive lab work, & only you can make this decision- it's taking a chance, yes, as antibiotics are a bit hard on the snake's body (some drugs more than others) & they are best used when knowledgeably targeting the actual pathogen at hand.
Did they say WHICH antibiotic they suggest be used, & how it will be administered? (I'm asking for a reason...)
You might ask this vet more questions before deciding whether to proceed- they should answer them.
Another thing is that snakes generally have solid pus, & abscesses generally require surgical removal, so antibiotics might do very little, unless you left something out? Is this vet experienced with snakes? Are they listed with ARAV? https://arav.site-ym.com/search/custom.asp?id=3661 I ask because medical care for snakes is very different from other animals, as are which medications are safe to use. This is just my thoughts- you might wait for a Armiyana or Caitlin to weigh in on this also. I wouldn't make a snap decision just yet.
I see that Armiyana already replied while I was typing...![]()