Anaphylaxis Patient friendly summary

Abdominal pain, diarrhea, and vomiting are some of the symptoms associated with anaphylaxis.

Anaphylaxis is a very severe hypersensitivity to an allergen. Allergens are any substances that cause allergies. This condition affects many systems of the body at the same time:

  • Skin: hives, itchiness, and flushing
  • Respiratory: shortness of breath
  • Gastrointestinal: abdominal pain, diarrhea, and vomiting
  • Cardiovascular: coronary artery spasm and possible heart attack
  • Nervous: drop in blood pressure, possible loss of bladder control, and anxiety

Anaphylaxis usually occurs suddenly and requires emergency treatment.

Risk factors

The most common causes of anaphylaxis are:

  • Foods
  • Venom from insect bites or stings
  • Drugs
  • Frequency of exposure to an allergen

Sunlight exposure and anaphylaxis risk

Several studies have identified links between severe allergies, seasons of birth, and vitamin D:

  • One U.S. study identified regional differences in EpiPen prescriptions in 2004. (EpiPen [Day Pharmaceuticals, California] is an injection used to treat severe allergies.) The most EpiPen prescriptions were filled in the Northeast. The least number of prescriptions were filled in the Southwest. This variation may be related to summertime solar ultraviolet-B (UVB) doses. There is more UVB light in the Southwest and less in the Northeast.
  • There was a significant increase in EpiPen prescription rates in Australia as latitudes increased. Higher latitudes are farther from the equator and have less sun.
  • Evidence suggests that season of birth may be associated with food allergies. Therefore, vitamin D may support a developing immune system whether in early childhood, in utero, or both.

Vitamin D and Anaphylaxis

How vitamin D works

Vitamin D may help severe allergies because it:

  • Reduces immunoglobulin E (IgE), a type of antibody: Higher IgE levels are associated with increased risk of anaphylaxis. As vitamin D levels increase in value from winter to summer, IgE levels drop.
  • Reduces inflammation: Calcitriol is the hormonal version of vitamin D. It acts on the immune system and reduces inflammation when the body is fighting allergies.


Vitamin D may lower the risk of food allergies and anaphylaxis while the baby is in utero, in early childhood, and later in life.

In Finland, maternal diet affected the risk of food allergies in children up to five years of age. Mothers who took more vitamin D (even low doses) during pregnancy had children with less sensitivity to food allergens.


There are no reported studies indicating that vitamin D may be used to treat allergies or anaphylaxis. It seems unlikely that vitamin D would be helpful for anaphylaxis as this condition usually requires emergency treatment and vitamin D's effects would take at least a day or two to appear.

Find out more...

Do you want to find out more and see the research upon which this summary is based?  Read our detailed evidence summary on anaphylaxis.

Page last edited: 03 June 2011