Anaphylaxis is a severe allergic reaction. It can lead to a potentially fatal condition known as anaphylactic shock. Common substances that the body reacts against include food, insect bites, venom, and medication. These are called allergens.
Food allergy is the main cause of anaphylaxis outside of the hospital, according to Food Allergy Research and Education (FARE).
Anaphylactic reaction to food is responsible for one emergency department visit every 6 minutes in the United States. Most affected are teenagers and young adults at risk of fatal anaphylaxis caused by food.
Results of a public survey of 1,000 people has suggested that the prevalence of anaphylaxis in the general population is "at least 1.6 percent and probably higher." In this population, the most common triggers reported were medications, at 34 percent, foods at 31 percent, and insect stings at 20 percent.
One study has estimated that the chance of an American experiencing anaphylaxis in their lifetime is between 0.5 percent and 2 percent. In the U.S., anaphylaxis is fatal in 0.65 percent to 2 percent of cases. The numbers of hospitalizations due to anaphylaxis have risen in recent years.
Contents of this article:
What happens in anaphylaxis?
For some people, a bee sting could be fatal.
Anaphylaxis happens when the body reacts badly to an allergen. When exposed to the allergen, the body produces large amounts of histamine.
The histamine triggers an inflammatory response, treating the substance as if it were a threat to health, like a harmful bacterium or virus.
This response can lead to a dilation of the blood vessels, a sudden drop in blood pressure, loss of consciousness, and shock.
The airways narrow, making breathing difficult. The blood vessels may leak, resulting in edema, or swelling, in surrounding tissue.
The reaction may happen at once, within hours, or, very occasionally, some days after coming into contact with the allergen.
Symptoms of anaphylaxis
Symptoms that may develop as a result of this reaction include:
- Difficulty breathing, wheezing, shortness of breath, tightness in the throat and chest, cough, hoarse voice, and chest pain
- Low blood pressure and poor circulation leading to pale blue skin, a low pulse, dizziness, faintness, shock, and loss of consciousness
- Trouble swallowing
- Itchy mouth or throat and nasal congestion
- Feeling as if something is stuck to the tongue, or in the throat
- A full and heavy feeling in the tongue
- Swelling and itchiness on the skin, with hives, warmth, redness, and a rash
- Stomach pain and cramps, with nausea, vomiting and diarrhea
- Anxiety and a feeling of impending doom
- Swelling in the feet, hands, lips, eyes, and sometimes the genitals.
The person may also have itchy, red, watery eyes, a headache, and cramping of the uterus, and they may have a metallic taste in the mouth.
Severe breathing difficulties, a serious drop in blood pressure, or both can lead to shock and this can be fatal.
First aid for anaphylaxis
If a person starts to show severe allergic symptoms, urgent medical attention is needed.
People who know they are allergic may carry an Epipen.
First aid for anaphylaxis includes removing the allergen, if possible, and calling for emergency help.
If possible, a bystander should find out if the patient has a history of allergy.
If the patient knows they are allergic, they may have medication in the form of an adrenalin injection kit, such as an Epipen, that they can use. Whoever is accompanying the person can help them to use this.
An Epipen provides a dose of Epinephrine, a form of adrenalin.
While waiting for help, the person who is with the patient should reassure them and make sure that they are comfortable and that they can breathe.
To make breathing easier, the person should be kept sitting up, but if there is a drop in blood pressure, they should be laid down flat on the ground with their legs raised. If they faint, someone should make sure they are able to breathe. They can be placed in the recovery position.
Whoever stays with the patient should monitor their condition, and note whether they self-medicate, because health care workers will need to know about this. If possible, keep a sample of the item that cause the reaction and have it accompany the patient to the hospital.
If breathing stops completely, cardiopulmonary resuscitation (CPR) should be performed and continued until the rescue team arrives.
Treatment for anaphylaxis: Epinephrine, or adrenalin
Emergency help for a patient with severe anaphylaxis will be an epinephrine, or adrenalin, injection.
Wearing an allergy bracelet alerts others to the individual's risk.
Adrenalin, also known as epinephrine, works in several ways. It causes the blood vessels to constrict, and this decreases swelling and helps to increase blood pressure.
Adrenalin also helps to relax the muscles around the lung, and it prevents the release of additional allergic chemicals. This helps to stop the reaction from progressing further.
Most patients respond well to this treatment, and symptoms normally start to subside at this point.
If there is no improvement, the patient will receive another dose after 10 minutes.
Sometimes, symptoms subside after taking adrenalin, but then come back, so the patient may be kept under observation in the hospital for 24 hours.
For a less severe reaction, the doctor may give corticosteroid or antihistamine injections.
People who are prone to allergic reactions should have an allergy action plan. This may include carrying epinephrine auto-injectors, liaising with schools and employers, and carrying a medical alert bracelet.