Some people have an allergy to nefazodone. Would they also have a similar allegy to trazodone?

Not necessarily. They are different compounds with differing effects. However, anyone with an allergy to one med is at higher risk to be allergic to another. Going on and off meds repeatedly may sensitive you to a medication.
Allergy. No cross allergy. Each antidepressant has its own tolerability profile. Serzone is now extinct.

Related Questions

If you had an allergy to nefazodone, would you also have allergy to trazodone?

You might. It is not uncommon to have allergic reactions (ar's) to both Nefazodone and trazodone. It is easy to confuse ar's with medication side effects (se's). Common ar's are skin rashes, breathing problems, and chills/fever. Common se's for these medications include blurred vision, dry mouth, sedation, and GI problems. Check with your md to determine if your reactions were true ar's or se's! Read more...