Posted By Chris Packham
I hope that the following will be of some help.

1. Sensitisation to a substance does not of itself have any clinical manifestation. Allergic reactions to Gluteraldehyde are generally a type IV immune response. The reaction is seen on the next exposure after sensitisation has occurred.
2. If sensisation has occurred then what you will need to do is to refer the person to a dermatologist for patch testing. This is the only way that a clinical diagnosis for an allergic reaction can be made. Anything else is guesswork and could result in a misdiagnosis and inappropriate treatment.
3. Once sensitisation has occurred it is generally a permanent condition, so that any future exposure will result in an allergic reaction.
It is possible for the reaction to be one of intolerance, i.e. not a genuine allergic reaction. This could have similar symptoms as you describe.

So my action in such a situation would be:
a) Refer to a dermatologist who runs a regular contact dermatitis clinic with full details on the case.
b) On receipt of a diagnosis showing positive reaction to a substance consider how future exposure can be eliminated.
c) If there is no positive reaction to the substance, then you can conclude that this is not a genuine allergic reaction. There may, of course, be other reasons for her reaction which could need investigation. Actually, investigating a case such as this can be complex, with many different factors contributing to the problem.

If you need more on this feel free to contact me off the forum.

Chris