Never summarize as “allergic” to a medical professional; they need the details.

I indicate on medical forms that Vicodin gives me waking nightmare hallucinations, because it doesn’t kill me like an allergy, but they should be aware of what they’re in for if they do select it. (This straightforward disclosure has encouraged many years of good decisions by doctors who, I suspect, would rather not have my screams of terror interfering with their work :)