Manifestations cutanées de l’anaphylaxie (choc anaphylactique) (Pour les professionnels)

• Anaphylaxis is a severe form of allergic reaction to certain substances such as food, drugs, insect stings and others. These substances serve as stimuli which attract certain antibodies in the body known as IgE antibodies. These IgE antibodies are bound to mast cells in the skin. These mast cells release chemicals that are disseminated in the body and bring about reactions, one of which is manifested in the skin (Hypersensitivity reaction of type I).
• In severe anaphylaxis, there is the presence of urticaria which is a type of skin rash made up of pale red, raised, itchy bumps (like a nettlerash). There is also swelling of the tissue of the blood vessels and the skin. Complications may occur fast, such as low blood pressure and asthma. This is why anaphylaxis needs emergency treatment.

So what kinds of substances cause anaphylaxis?

• These substances may either be determined or undetermined (any substance can cause anaphylaxis). Food is a common cause of anaphylaxis. These foods that cause anaphylaxis include peanuts, seafood such as:

1. fish and shellfish
2. tree nuts such as brazil, almond and hazel nuts
3. eggs
4. milk
5. soy
6. sesame seeds
7. wheat.

• Children are the ones who are commonly affected by these food allergic reactions. Children may have food allergy either by eating, breathing or just touching these foods. In food allergies, skin manifestations are common, although fatalities can happen but are rare.
• Drugs are the second most common cause of anaphylaxis. Penicillin is the most common drug involved in drug anaphylaxis. Other drugs may also cause allergic reactions, such as:

1. sulfonamides
2. tetracyclines
3. vancomycin
4. cephalosporins
5. ciprofloxacin
6. aspirin
7. ibuprofen
8. diclofenac
9. naproxen
10. anesthetics
11. opioid analgesics…

• Another common cause of anaphylaxis is insect stings. Stings from bees and wasps such as those from the hymenoptera species have venoms which can cause anaphylaxis.
• There are other causes which may be uncommon such as latex rubber, vaccine components and intravenous/ injectable radiocontrast media.

So, how do you know whether you have anaphylaxis or not?

• You have to take note of your signs and symptoms, which may be skin reactions and difficulty of breathing after food intake. Drug or venom-induced anaphylaxis is more complicated because they more often produce shock, which is a medical emergency. You should suspect that anaphylaxis is responsible for your skin rashes once your symptoms occur within 5 to 60 minutes after you have taken in food or drug or after you have contact with the suspected allergen. However, allergic reactions may also occur after several hours or even after 3 to 4 days later. If your symptoms occur fast, you better go to the emergency treatment because faster progression of symptoms usually indicates a severe and life threatening condition.
• In more than 85% of cases, the skin in one part or in all parts of the body has a red rash which itches and swells. The skin may feel hot over these areas.
• In 50% of cases there may be difficulty of breathing, shortness of breath, tightness of the throat, sneezing, coughing, and wheezing. There may also be congestion in the nose, hoarseness of the throat and swelling of the lips or tongue.
• Other symptoms include stomach cramps, nausea, vomiting, and diarrhea. More complicated symptoms which need immediate treatment in the emergency room are chest pain, rapid or irregular heart rate, low blood pressure, confusion, dizziness, collapse and tremors.
• If you feel these symptoms, you better proceed to the emergency room for immediate management. Patients with anaphylaxis are stabilized to prevent shock, airway swelling or difficulty of breathing. Antihistamines may be given along with corticosteroids, epinephrine and other drugs. There is now a self-injectable epinephrine (adrenaline) pen available in the market today which is prescribed to people with a history of an anaphylactic reaction. However, before using this, ask your doctor for directions on how to use it. You should form a fist around the pen and pull off grey cap. Place black end against outer mid thigh. Push down hard until a click is heard or felt and hold in place for 10 seconds. Remove the pen. Massage the injection site for a few seconds.

Note: Anaphylaxis is not exactly speaking a skin allergy (Anaphylaxis is more exactly a Type I Hypersensitivity reaction), but for sake of reading simplicity, this term is still used here.

Contributors: Dr Christophe HSU – dermatologist. Geneva, Switzerland