I would like your help in the evaluation of a 17 year-old male with a history of hives related to contact with grass. The first episode occurred about 1 year ago when he was walking in the grass. He first noticed a sense of flushing and warmth along with itching that spread to his legs, arms and face associated with swelling of the face and he took some Cetirizine and his symptoms resolved spontaneously without recurrence. 2nd episode occurred in February this year where he was in track and ran at school (not associated with contact with grass). On the 2nd day he started developing generalized hives, but the pruritus was more intense along with shortness of breath and feeling unwell. He went to an urgent care center and was given a medrol pack and antihistamines for a few days and his symptoms completely resolved. He however continued to do track but did not run with the same intensity and did not have any recurrence for a while. 3rd episode was in October this year and he stepped into the grass wearing flip flops on the way to retail store and within minutes started developing rapid intense hives associated with swelling of his lips and tongue but no choking, light headedness or dizziness. He went to urgent care where he was given Decadron, epinephrine and Benadryl. His symptoms started improving in 1 hr and his symptoms spontaneously resolved without recurrence.

His history was negative for the usual suspects foods, medications, insect stings, contact with chemicals or latex. Interval labs including LFTS, serum tryptase, ESR, CBC with diff were all normal. He does not have a history of atopy and skin testing was not done to any aeroallergens thus far as I am not sure there is a relationship with contact with some grass and his symptoms. He is currently equipped with an Epipen but I was wondering if there is any further work-up needed to investigate his symptoms.


Thank you for your inquiry.

I am in agreement with you in that more than likely the history of exposure to grass is probably a "red herring." However, since you presented the problem as related to grass, and it is so easy to see if there is an IgE-mediated sensitivity, I would at least test him to this one allergen. As noted, my assumption is that the test will be negative. However, this is indicated if for no other reason than to "clear the air" for the patient.

There was one episode related to exercise, and it is unclear from your email as to the extent of exertion (we know he was at least walking) related to the other events. So exercise induced urticarial/anaphylaxis must be kept in mind.

The other thing that is important to keep in mind is that the vast majority of episodes of acute urticaria/anaphylaxis are idiopathic in adults and adolescents who have no history of atopy (1).

You have done more than enough laboratory work, and I do not feel any other blood work would be of help to you. I think if you do not find a positive test to grass, you will be forced to simply make a diagnosis of recurrent idiopathic urticaria/anaphylaxis. If this is the case, of course the most important element of his treatment would be to maintain an automatic epinephrine injector and use it appropriately. You could also consider pretreatment with antihistamines if episodes began to occur more frequently.

The only other laboratory test that I might consider if the episodes continued would be a repeat tryptase. If it was above 11 you would consider doing a bone marrow. If it was 20 or above, a bone marrow would clearly be indicated.

In summary, my best guess is that your patient is experiencing what we would normally call "recurrent idiopathic urticaria/anaphylaxis" and no cause will become evident. No further workup except perhaps skin testing him to grass, in my opinion, is indicated at this time. If episodes worsen or become more frequent, you could consider repeating a serum tryptase and also pretreatment with antihistamines.

Thank you again for your inquiry and we hope this response is helpful to you.


1. Webb L and Lieberman P. Anaphylaxis: A Review of 601 Cases. Annals of Allergy, Asthma, and Immunology, July 2006; 97(1):39-43.

Phil Lieberman, M.D.

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