What you Should Know About Severe Allergic Reactions

Increasing pollution and decreasing immunity is causing many people, especially urban Indians, to develop allergies.

What is an allergy?

An allergy is a hypersensitivity disorder of the immune system. It is the body’s reaction to a common harmless substance in the environment.

How an allergy occurs

When the human body comes into contact with an allergen (a substance that causes the allergy), it initiates certain responses. Components like mast cells, basophils and some white blood cells are released in response to an antibody (a substance produced by the body when it detects a foreign substance called an antigen). Also, certain chemicals like histamines and cytokines are produced, causing inflammation. In some cases, angioedema and swelling of eyes, lips and other parts of the body are seen, and if the tissues inside the throat get swollen, they can block the airway causing death.

Severe Allergic Reactions

Some allergic reactions can be fatal if not treated immediately

Types of Severe Allergic Reactions

There are three severe allergic reactions which require prompt medical treatment as the person’s life can be in jeopardy, namely:

1. Anaphylactic Shock

2. Anaphylactoid Reaction

3. Angioneurotic Oedema.

Anaphylactic Shock

It is a severe allergic reaction involving the entire body, causing low blood pressure and inability to breathe — which can be life-threatening if not recognized and treated timely.

This severe allergic response occurs to an antigen that the body has been exposed to earlier, but the antibody response at that time had been minor. In some cases, the first reaction wouldn’t have occurred. So this time, the body assumes that the antigen is a foreign substance and launches a major attack against it.

The release of Immunoglobulin E is a given in a true anaphylactic reaction. Other chemicals like histamine are released, in addition to some chemicals called mediators, which act on the body to cause the symptoms.

Causes of Anaphylactic Shock

• Food allergies–foods like nuts, shellfish, milk, soy and wheat
• Food additives like sulfites
• Drug allergies – penicillin, aspirin and others
• Stings and insect bites – bumblebees, honeybees, wasps and fire ants
• Idiopathic – the cause is not known
• Blood or blood products during a transfusion
• Dyes used in radiologic procedures
• Pollen and airborne allergens rarely cause an anaphylactic reaction.

Symptoms of Anaphylactic Shock

People who suffer from eczema, hay fever and asthma are more likely to have an anaphylactic reaction. This reaction occurs rapidly in most cases and no time should be lost in taking the person to the hospital. The symptoms primarily involve the heart, airways and skin primarily.

• Hives; erythema (redness of skin); wheals (raised bumps)
• Swelling of eyelids, lips, hands, feet; angioneurotic edema, which can be fatal
• Anxiety, confusion, dizziness
• Abdominal pain, vomiting, nausea, abdominal cramps, difficulty in swallowing
• Difficulty in breathing due to swelling of the tongue or airways
• Nasal congestion, sneezing , cough or hoarseness
• Fluid accumulation in the lungs (pulmonary edema)
• Fainting; palpitations, rapid pulse
• Loss of consciousness due to dangerously low blood pressure called ‘shock’
• Irregular heartbeat
• Cardiac arrest (Learn More : LIFE AFTER A CARDIAC ARREST)

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Diagnosing Anaphylactic Shock

The condition is diagnosed on the basis of accurate history from the patient or relatives and by examination. No test can reveal this diagnosis.

Treatment for Anaphylactic Shock

It is divided into immediate treatment by the persons closest to him and emergency treatment in a well-equipped hospital.

Immediate measures

• Pay attention to the ABCs of resuscitation. A is for airway. In case of swelling of the throat, the airway may get blocked. B is for breathing; if oxygen is available (in the ambulance) give it and C is for circulation, which involves the blood pressure and heart condition.
• If the stinger of the bee is seen on the skin, gently remove it with a fingernail or edge of a plastic credit card.
• If the person has an emergency epinephrine injection, help him inject it in his thigh. After administering it, do not waste time. Ensure that the person is taken to the hospital without delay.
• Raise the person’s feet about 12 inches higher than his head to ensure good blood supply to his brain.
• Do not give oral medicines to a person if he has trouble breathing.

Treatment in Casualty

The first step is to secure the airway. A tube may be passed from the mouth to the windpipe to maintain a patent airway (endotracheal intubation). In rare cases, an opening in the throat is made by a simple surgery (tracheostomy).

Drugs given intravenously are epinephrine (life-saving in anaphylaxis), dopamine to restore the blood pressure, steroids and anti-histamines.

Complications that may occur in case of Anaphylactic Shock

In rare cases, death may occur due to cardiac arrest (heart attack) or bronchospasm (severe constriction of the small air passages in the lungs).

Preventing Anaphylactic Shock

• While buying foods, read labels carefully. When eating outside mention expressly, the foods you are allergic to.
• Avoid triggers such as foods or drugs that have caused even a mild allergy in the past.
• Wear a tag mentioning what you are allergic to specific substances in the form of a necklace or bracelet.
• If a child has allergies, introduce only one new food at a time and in small quantities.
• If you are prone to serious allergic reactions, ask your doctor if you should carry chewable diphenhydramine or injectable epinephrine with you at all times.

Anaphylactoid Reaction

This is a reaction similar to anaphylactic shock but without the release of Immunoglobulin E. However the symptoms, treatment and risks are the same.

Angioneurotic Oedema or Angioedema

It is an extreme manifestation of urticaria. It causes massive swelling and affects the face, lips and limbs. It has a sudden onset and is generally drug induced.

Symptoms of Angioneurotic Oedema

Sudden diffuse swelling of the eyelids and lips is common with inability to open the eyes. Face looks distorted. Other sites include hands, forearms, feet and genitals – scrotum and penis in men and vulva in women.The most dangerous involvement is swelling of the larynx (upper part of the windpipe and voicebox).If the inner lining of the larynx (laryngeal mucosa) swells up, it causes laryngeal oedema, which may be fatal due to the airway getting completely blocked.

Treatment for Angioneurotic Oedema

The person must be rushed to the hospital. Intra-venous antihistamines, steroids like hydrocortisone and if required, epinephrine is administered.If the airway is blocked, the same measures must be taken as in anaphylactic shock. The person must be observed carefully for the next few hours.

Prevention of Angioneurotic Oedema

If the trigger is identified it must be strictly avoided