Hives, also named urticaria, welts or nettle rash, is a common manifestation of food allergy: around 20% of acute hives attacks are related to the ingestion of an allergenic food, as milk, nuts, eggs, chocolate, fish or some types of fruit.

Food allergy related hives reaction is almost immediate, after hours or at least days: red, itchy, swollen areas suddenly appear on the skin all over the body, the face, lips, tongue, throat or ears. Itchy areas vary in size, from very small to several centimeters width. They typically itch severely, sting, or burn, and often have a pale border.

Larger areas, known as plaques, result from the joining of several smaller areas.

Hives may last for hours, or up to several days before it disappears.

Why hives is related to food allergy?

The allergic mechanism is responsible for the hives manifestation, because of chemicals that are released during the abnormal immune reaction, mainly histamine.

When histamine circulates in the inner cells of the skin and of the skin capillaries, the endothelial cells, provokes an inflammatory reaction with a leakage of liquids from the capillaries, resulting in itchy skin lesion.

Histamine may also be released by causes other than food allergy, as infections, drugs, viruses or bacteria or other physical substances (water, heath, cold, sun, etc.)

Types of hives

Food allergy related hives is an allergic hives: histamine and the other inflammatory substances are released from activated immune cells. These cells have been activated by the binding with IgE antibodies, produced by the allergen-antibody interaction.

Mechanisms other that immune cells can cause histamine release and non allergic hives.

According to the time in which the itchy reaction disappears, we can classify acute hives, appearing few minutes after the allergen exposure and lasting from few hours to several weeks, and chronic hives, non allergy dependent, that persists for more than a month.

Hives and Edema

Skin edema is a condition strictly related to hives: fluids accumulate in the space between tissue cells resulting in swelling. Apart from itching, the area can also be less sensitive, due to the compression of sensorial nerves. Reason of this reaction is the same as for hives, the histamine released under the skin.

Edema frequently occurs everywhere but typically on the hands, on the face and the surrounding mucous areas: the mouth, tongue and throat. This condition is very dangerous because it may render breathing difficult. This reaction, the anaphylaxis, must be treated immediately in emergency hospital.

Diagnosis and treatment of hives

Generally, hives is easy to recognize optically from its appearance, and investigations may be useful only to determine the cause and, in case of a food allergic hives, the allergenic food. This is due to the elimination diet, removing all the possible allergenic foods from the diet one by one, identifying the offending food. A food diary can be a useful instrument, to annotate eated food and eventual reactions and to see if hives decreases.

To diminish hives reactions, but not to treat the causes, it may be useful some antihistamines medication that block the effects of histamine. These medications must be taken under medical control.

There are also some actions that are useful to reduce itching, as keeping the skin cool, avoiding getting hot from exercise and taking lukewarm baths.

The main suggestion is to not rub the itchy skin, eventually applying moisturising creams to reduce dryness and itch.