Allergens & Allergies -
extract from MedlinePlus,
A service of The US
National Library of Medicine and The Institute of Health.
Definition
An allergen is a
substance that can cause an allergic reaction. Allergens are substances that,
in some people, the immune system recognizes as "foreign" or
"dangerous" but cause no response for most people.
Information
Common allergens
include:
- Bacteria,
viruses, and animal parasites
- Chemicals
- Dust
- Drugs (such as
antibiotics, serums [vaccines])
- Foods (such as
milk, chocolate, strawberries, wheat)
- Perfumes
- Plants
- Pollen
- Smoke
See also (links to
MedlinePlus information pages on various types of allergies):
Allergies
Allergic reaction
Food allergy
Allergy to drugs
Antigen
Antibody
Update Date: 2/15/2007 Updated by: Donald
Accetta, MD, MPH, President, Allergy & Asthma Care, PC, Taunton, MA. Review
provided by VeriMed Healthcare Network.
Symptoms
Common symptoms of mild allergic reactions include:
- Rashes
- Hives (especially over the neck and face)
- Itching
- Nasal congestion
- Watery, red eyes
Symptoms that may
indicate a moderate or severe reaction
include:
- Swelling of the
face, eyes, or tongue
- Difficulty
swallowing
- Wheezing
- Fear or feeling
of apprehension or anxiety
- Abdominal cramps
or abdominal pain
- Nausea and
vomiting
- Weakness
- Dizziness or
light-headedness
- Chest discomfort
or tightness
- Difficulty
breathing
- Unconsciousness
First Aid
For a mild to moderate reaction:
1. Calm
and reassure the person having the reaction, as anxiety can worsen symptoms.
2. Try
to identify the allergen and have the person avoid further contact with it. If
the allergic reaction is from a honey bee sting, scrape the stinger off the
skin with something firm (such as a fingernail or plastic credit card). Do not
use tweezers; squeezing the stinger will release more venom.
3. If
the person develops an itchy rash, apply calamine lotion and cool compresses.
Avoid medicated lotions.
4. Watch
the person for signs of increasing distress.
5. Get
medical help. For a mild reaction, a physician may recommend over-the-counter
medications (such as antihistamines).
For a severe allergic reaction
(anaphylaxis):
1. Check
the person's airway, breathing and circulation (the ABC's of Basic Life
Support). A warning sign for dangerous throat swelling is a very hoarse or
whispered voice, or coarse sounds when the person is breathing air in. If the
victim is having difficulty breathing, is very weak, or is losing
consciousness, call for emergency medical assistance. If necessary, begin
rescue breathing and CPR.
2. Calm
and reassure the person.
3. If
the allergic reaction is from bee stings, scrape the stinger off the skin with
something firm (such as a fingernail or plastic credit card). Do not use
tweezers -- squeezing the stinger will release more venom.
4. If
the person has emergency allergy medication on hand, help the person take or
inject the medication. Avoid oral medication if the person is having difficulty
breathing.
5. Take
steps to prevent shock. Have the person lie flat, elevate the
person's feet about 12 inches, and cover him or her with a coat or blanket. DO
NOT place the person in this position if a head, neck, back, or leg injury is
suspected or if it causes discomfort.
6. If
the person loses consciousness, apply first aid for unconsciousness and call 911 or your local
emergency number.
DO NOT
- DO NOT Assume
that any allergy shots the person has already received will provide
complete protection.
- DO NOT Place a
pillow under the person’s head if he or she is having trouble breathing.
This can block the airway.
- DO NOT Give the
person anything by mouth if the person is having trouble breathing.
When
to Contact a Medical Professional
- The person's
allergic reaction is severe or rapidly worsening (over minutes -- see
above).
- The person has a
history of severe allergic reactions (check for a medical ID tag).
Prevention
- Avoid triggers
such as foods and medications that have caused an allergic reaction, even
a mild one, in the past. This includes detailed questioning about
ingredients when eating away from home. Ingredient labels should also be
carefully examined.
- If you have a
child who is allergic to certain foods, introduce one new food at a time
so you can recognize an allergic reaction.
- A medical ID tag
should be worn by people who know that they have serious allergic
reactions.
- If you have a
history of a serious allergic reactions, carry emergency medications (such
as diphenihydramine and injectable epinephrine or a bee sting kit)
according to your health care provider’s instructions.
- Do not use your injectable epinephrine on anyone else. They may have
a condition (such as a heart problem) that could be affected by this drug.
Update
Date: 5/3/2006 Updated by: David A.
Kaufman, M.D., Assistant Professor, Division of Pulmonary, Critical Care &
Sleep Medicine, Mount Sinai School of Medicine, New York, NY. Review provided by
VeriMed Healthcare Network.
