An allergic reaction is the body's way of responding to an "invader." When the body senses a foreign substance, called an antigen, the immune system is triggered. The immune system normally protects the body from harmful agents such as bacteria and toxins. Its overreaction to a harmless substance (an allergen) is called a hypersensitivity reaction, or an allergic, reaction.
See the complete A-Z list of all the Allergies related information or browse the current list of select resources.
Allergies Related Resources
- What Are the Best Treatments for Allergic Conjunctivitis?
- Does Immunotherapy Work for Allergies?
- Is Sinus Infection Contagious?
- Sinus Infection (Sinusitis)
- What Causes Angioedema?
- Allergy Shots
- Poison Ivy, Oak, and Sumac
- Food Allergy
- Allergic Reaction
- Hay Fever
- Sinus Headache
- Hives and Angioedema
- Bee and Wasp Stings
- Insect Bites
- Drug Allergy
- olopatadine (nasal) (Patanase) (Patanase)
- ciclesonide nasal (Omnaris, Zetonna) (Omnaris)
- levocetirizine (Xyzal) (Xyzal)
- acetaminophen, diphenhydramine, and phenylephrine (Benadryl Allergy & Cold) (Benadryl Allergy & Cold, Benadryl Allergy & Sinus Headache, Sudafed PE Severe Cold and more)
- desloratadine and pseudoephedrine (Clarinex-D 12 Hour, Clarinex-D 24 Hour) (Clarinex-D 12 Hour, Clarinex-D 24 Hour)
- chlorpheniramine and codeine (Codar AR, Tuzistra XR) (Cotab A, Cotab AX, Notuss-AC and more)
- epinastine ophthalmic (Elestat) (Elestat)
- omalizumab (Xolair, Xolair Prefilled Syringe) (Xolair)
- diphenhydramine and phenylephrine (Benadryl-D Children''s Allergy & Sinus) (Alahist LQ, Aldex-CT, Children's Triacting Night Time and more)
- dexchlorpheniramine and pseudoephedrine (AllerDur, Deltuss DP, Rescon) (AllerDur, Duotan PD, Tanafed DP)
- desloratadine (Clarinex, Clarinex Reditabs) (Clarinex, Clarinex Reditabs)
- cetirizine and pseudoephedrine (All Day Allergy-D, Allergy D-12, Allergy Relief Nasal Decongestant) (All Day Allergy-D, Zyrtec-D)
- fluticasone nasal (Childrens Flonase, Flonase, Flonase Sensimist) (Flonase, Veramyst)
- flunisolide nasal (Nasalide) (Nasarel)
- beclomethasone nasal (Beconase AQ, Qnasl, Vancenase AQ) (Beconase AQ)
Allergies Images and Slideshows
- Nasal Allergy Attack: Causes, Triggers, Treatments
- Home Health: Meet the Bugs That Live In Your House
- Nasal Irrigation: Natural Relief for Cold & Allergy Symptoms
- Bad Bugs: Identify Insects and Bug Bites
- Allergy: Life-Threatening Allergy Triggers
- Sinus Infection: Sinusitis Dos and Don'ts
- Allergies: Common Plants and Trees That Trigger Allergies
- Allergies: 10 Ways to Reduce Mold Allergies
- Allergies: Myths and Facts About Seasonal Allergies
- Healthy Home: How Often Should This Be Cleaned?
- Top 13 Ways to Tame Eye Allergies
- Picture of Photoallergic Reaction
- Picture of Nickel Contact Dermatitis from Necklace
- Picture of Allergic Contact Dermatitis (Tattoo)
- Picture of Allergic Contact Dermatitis
- Even a Few Days of Steroids May Be Risky, New Study Suggests
- Frustration Mounts as EpiPen Shortage Hits 1 Year
- How do you get autoimmune disease?
- Do Autoimmune Diseases Run in Families?
- What Is the Most Common Autoimmune Disease?
- What Autoimmune Diseases Affect the Eyes?
- Equivocal Results for Peanut Allergy Skin Patch
- FDA Extends Some EpiPen Expiration Dates to Fight Shortages
- Recall: Tyson Foods Chicken Products
- Recall: Canned Pasta Shells and Spaghetti
- Global EpiPen Recall Now Includes U.S.
- AAP Updates Guidance on Epinephrine Use for Anaphylaxis
- Skin Patch to Treat Peanut Allergy
- Genetic Explanation for Frustrating Syndrome
- The True Cost of EpiPen Coupons