Below is information about first aid that is required if you noticed allergic reaction.

For a mild to moderate allergic reaction:

Calm and reassure the person having the reaction. Anxiety can make symptoms worse.

Try to identify the allergen and have the person avoid further contact with it. If the allergic reaction is from a 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.

1. If the person develops an itchy rash, apply cool compresses and an over-the-counter hydrocortisone cream.
2. Watch the person for signs of increasing distress.
3. Get medical help. For a mild reaction, a health care provider may recommend over-the-counter medications, such as antihistamines.

For a severe allergic reaction (anaphylaxis), check the person's airway, breathing, and circulation (the ABC's of Basic Life Support). A warning sign of dangerous throat swelling is a very hoarse or whispered voice, or coarse sounds when the person is breathing in air. If necessary, begin rescue breathing and CPR.

1. Call emergency.
2. Calm and reassure the person.
3. If the allergic reaction is from a 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.
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, raise 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.

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 airways.
• Do not give the person anything by mouth if the person is having trouble breathing.

When to Contact a Medical Professional

Call emergency for medical assistance right away if:

• The person is having a severe allergic reaction. Do not wait to see if the reaction is getting worse.
• The person has a history of severe allergic reactions (check for a medical ID tag).

Source: http://www.nlm.nih.gov/medlineplus/ency/article/000005.htm