Pharmacists: do anti-biotics (& therefore allergise to anti-biotics) live in families (so you can predict reactions)

[KatyMac]

After many, many years of taking Trimethoprim I had an allergic reaction to it

Should I look out for any other anti-biotics?

I'm allergic to trimethoprim, and also to septrin, which AFAIK is related to it. I'm also mildly allergic to penicillin.

As far as I know no other members of my family have these allergies.

Disclaimer: I'm not a pharmacist or a doctor :)

A vet so have pharmaceutical training. Antibiotic sensitivity can run in families yes. Antibiotics belong to family groups trimethoprim belongs to the sulphonamides very few of which are still used, they have totally different pharmaceutical characteristics to other families of antibiotics. This makes you no more likely to react to another group than anyone else.
Some groups are more closely related for example penicillins and cephalosporins so there is often cross reactions between these groups.

Septrin is just a trade name for trimethoprim so actually the same thing.

Thanks