Allergies and the Histamine Connection

HOW IT ALL WORKS

Certain substances cause our body’s immune system to overreact and produce histamine as a response to proteins found in foods, insect venom, or airborne allergens.  Normally these agents are inhaled or absorbed through the skin.  The body’s immune system creates antibodies to attack the foreign substance by releasing chemical histamines in the body.

WHAT CAN HAPPEN

When too much histamine is released into the body, several allergy symptoms may occur.  These include skin irritations, such as rashes, hives or eczema.  The eyes are also affected and may become watery, inflamed, irritated or scratchy.  Nasal passages can become swollen, and airways congested with runny nose and sneezing.  Too much histamine in the airways may bring about allergy-induced asthma as well.  This can lead to shortness of breath, coughing and wheezing.

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The Antihistamine Solution

Antihistamines are used to treat allergy symptoms and come in pill form, liquids, tablets, and capsules.

Antihistamines treat:

• Skin rashes and hives

• Runny nose, sneezing, congestion, or itching

• Nasal passage swelling

• Runny, itchy eyes

Treatment for an Allergic Reaction

The body releases chemicals known as, “histamines” as a response to contact with allergens such as pet dander, pollen, ragweed or dust mites, for example.  This causes the swelling, itching or stuffiness that accompany an allergic reaction.  Antihistamines work to either reduce the level of histamine released in the body, or block it altogether to lessen allergy symptoms.

Allergy treatments may include medications such as steroids, allergy shots, or antihistamines.

These may be either prescribed by a physician or purchased OTC (over-the-counter).

Antihistamines: These are used to treat allergy symptoms and generally fall into two categories, sedating and non-sedating.  Older antihistamines fall into the first category.  These medications relieve allergy symptoms, but cause drowsiness, and several other side effects such as dry mouth.  Non-sedating antihistamines, often considered a newer class of medications do not cause as much drowsiness.

All antihistamines work to lessen or prevent the amount of histamine that causes an allergic reaction in the body such as, swelling, itching, tearing, and breathing issues and secretions.

Antihistamines come in pill form as creams, nasal sprays, lotions, nose drops, and eye drops.

Other allergy drugs may include:

Corticosteroids: These work to reduce inflammation and include creams, ointments, nasal sprays, and tablets.

Mast cell stabilizers: These must be taken regularly to prevent allergic reactions.  Some inhalers such as (Cromolyn Sodium) may be used for the prevention of asthma.  

Leukotriene inhibitors: These drugs target specific leukotriene receptors in the body to reduce allergic symptoms.

Nasal anticholinergics: These medications work to reduce nasal discharge only.

Decongestants: These drugs constrict blood vessels in the nose, which help limit the secretions that come from the inner lining.  They are available in nasal sprays, liquids, and pills.

Immunomodulators: These help to relieve skin allergies and are topical.

Auto injectable epinephrine: This drug application is used to treat anaphylaxis, a severe allergic response to food, insect venom, or other substances.

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Urticaria—The Management and Treatment of Hives

Hives, also known as, “urticaria” will affect about 20 percent of people in their lifetime.  Several different substances, causing an allergic reaction that creates itchy patches of skin that become swollen red welts, trigger this skin condition.  Certain activities may exacerbate hives such as, stress, alcohol, or exercise.

Symptoms

The symptoms of hives are itchy, raised, red or skin-colored bumps.  “Blanching” also occurs when the center of a red hive is pressed and it turns white.

Triggers

Common triggers include:

• Food Allergies (Food allergy rash)—Peanuts, eggs, nuts, shellfish

• Medications—Antibiotics, Ibuprofen, aspirin

• Insect venom—Bee sting allergy

• Physical stimuli—Sun, heat, cold

• Latex allergy

• Blood transfusions

• Infections—viral or bacterial

• Pet dander

• Plants—pollen, certain plants such as poison ivy, poison oak

Allergist Prescribed/OTC Medication

Treatment for hives includes both low-sedating and non-sedating antihistamines available by prescription or over-the-counter.  These may be taken along with anti-itch creams or salves, or cold compresses to reduce the swelling from hives.  Severe urticaria may require a temporary steroid such as Prednisone, a corticosteroid medication, or an immune modulator to reduce more severe symptoms.  In cases where the tongue or lips swell, or breathing is affected, a physician may prescribe an Epinephrine injector to be kept on hand in case of anaphylaxis, a potentially fatal severe allergic response.

It is important to identify, avoid, and eliminate triggers if possible including:

• A food allergy or foods that may cause an allergic response

• Scratching or rubbing

• Harsh soaps

• Pressure from tight-fitting clothing

• Temperature, including cold air or water

• Excessive sun exposure

• Specific medications

Chronic Hives—Not Forever

Chronic hives may occur if urticarial symptoms exist for more than six weeks.  If no known cause can be found for the condition, it is said to be, “idiopathic”, or “unknown”.  Many of these cases can be linked to immune disorders, however.  Chronic hives may also be associated with other medical conditions, such as cancer, thyroid disease, or other hormonal disorders.  In general, even chronic hives disappear over time, however.

Anaphylactic Shock—A Life-threatening Condition

This potentially fatal condition occurs as a severe allergic response toward a particular substance.  When this happens, the body can quickly shut down.   Breathing becomes labored, and blood pressure drops rapidly.  Thinking becomes unclear as the brain becomes starved for oxygen.  Cell-fluids in the throat can cause it to swell shut and death can occur within three to four minutes of exposure to a specific allergen.

Anaphylaxis is a severe reaction to a food allergy such as peanuts or seafood.  It can also occur in persons allergic to bee stings or other insect venom. This is a life-threatening condition that needs emergency medical treatment to prevent anaphylactic shock.  It is important to note that the body may not react to initial exposure, but may produce a large amount of histamine upon subsequent episodes of exposure to specific allergens.

General symptoms of anaphylaxis may develop within seconds or minutes and include:

• Pain in the abdomen

• Abnormal breathing sounds

• Anxiety

• Tightness in the chest

• Cough

• Diarrhea

• Breathing difficulties

• Swallowing difficulties

• Light-headedness, dizziness

• Hives, itching

• Nasal congestion

• Nausea, vomiting

• Heart palpitations

• Skin redness

• Slurred speech

• Swelling in the eyes, face, or tongue

• Unconsciousness

• Wheezing

Emergency Medical Care

At this time, an injection of the hormone, epinephrine, (which is naturally produced in the adrenal glands) is the only treatment for anaphylactic shock.  This works to open the airways by constricting the blood vessels in the body.  Unfortunately however, the effects of an injection only last about 10-20 minutes and the drug must be administered before, or at the onset of symptoms.  It is critical to get help immediately upon exposure to a known allergic substance that could lead to anaphylaxis.

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