No Reaction during Allergy testing

My girlfriend had an allergy test today because of her severe asthma.  She didn't react to a single thing, including the histamine control.  I was just wondering what could cause her to not react to anything, including the control?

Any information would be greatly appreciated.

Thanks

[National Jewish Health]

It is possible that your girlfriend is the relatively rare allergic person who simply has diminished allergen skin test reactivity.  False negativity, is another matter and the most common causes of total skin test negativity, including histamine, would be: 1)  extracts of poor initial or subsequent loss of potency; (2) drugs, especially antihistamines, that modulate the allergic reaction; (3) diseases, severe debilitating or immunodeficiency diseases  (4) reduced reactivity of the skin in infants and elderly patients; (5) improper technique (no or weak puncture); (6) UV exposure; (7) too short/too long an interval from the injection to the interpreted reaction

The most commonly performed skin tests are called ***** skin tests and, with these, the histamine and allergens are injected very superficially.  In some instances, these persons will react to deeper injections (intradermal).   History of an observed association between exposures to known allergens and worsening asthma can also provide useful information and guide avoidance of precipitants as can any history of seasonal worsening.

You would do well to discuss this with her allergist, asking if any of the above reasons for true or false negative results might be relevant and, especially, if further testing is warranted.  You might also ask about other types of testing, such as RAST testing.  It would also be of interest to determine if your friend exhibits any of the other signs of allergic disease such as increased numbers of eosinophils in blood and/or sputum and serum IgE levels.

If her severe asthma is not well controlled, it could be because her therapy is sub-optimum, either because of non-prescription or ineffective self-administration.  You should also discuss this with her allergist.

Good luck