Allergic reactions without answers

Chronic hives are a common problem in the general population and in my practice. Children and adults can suffer daily itching and hives for months or years without explanation. However, symptoms often resolve spontaneously and most importantly, the risk of a severe reaction is very low.

On the other hand, there is a separate condition called idiopathic anaphylaxis. People with this condition will have more severe allergic reactions; symptoms may include hives and swelling but there may also be upper airway obstruction, wheezing, shortness of breath, decreased blood pressure or fainting.

If a patient presents to the office after having a severe reaction, my primary goal is to identify what caused the reaction. Subsequent avoidance can prevent future problems. The most common (known) causes include foods, medications and stings. Unfortunately, a thorough history and physical exam may night identify a cause (or even a suspect). This situation occurs in 30-60% of adults and up to 10% of children. Risk factors include female gender and reported penicillin allergy.

Here are some possible explanations for idiopathic anaphylaxis:

  • Hidden food allergens. Expanding testing to include a large food panel may help to identify the cause. Unfortunately studies have shown little success, finding a cause in only 7% of cases. Other studies have ruled out food preservatives as causes of idiopathic anaphylaxis, including sulfites, MSG and aspartame.
  • Female hormones.
  • Immune abnormalities.
  • Increased sensitivity to histamine.
  • Autoimmune disease.
  • Delayed allergy to beef, pork or lamb. An allergic reaction to the oligosaccharide alpha-gal. Transmitted by the Lone Star tick.
  • Conditions which mimic anaphylaxis: somatoform┬ádisorder, scromboidosis (poisoning form “spoiled” fish).

Here are some tests that may be done:

  • Skin (or blood) testing to foods and/or medications.
  • Serum anti-alpha-gal IgE.
  • Tryptase level. Prostaglandin D2.
  • Urinary histamine metabolites.
  • Genetic analysis.

Here are possible treatments:

  • Anti-histamines.
  • Oral Steroids.
  • Oral albuterol.

 

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