Allergies are exaggerated immune responses to environmental triggers known as allergens. Allergies are very common, and about 50 million people in North America suffer from allergies. One of the most common forms of allergy is allergic rhinitis ("hay fever"), which produces symptoms like
- nasal congestion,
- itchy and watery eyes,
- stuffy or runny nose,
- scratchy or sore throat,
- throat clearing,
- cough from postnasal drip.
The symptoms of hay fever can, in turn, lead to fatigue and lethargy. Other types of allergic reactions can involve the skin (hives and itching). Anaphylactic shock is a severe form of allergic reaction that can be life-threatening. In anaphylactic shock, there is swelling of the throat and difficulty breathing. Asthma is also related to allergies in many cases.
The symptoms of allergies can sometimes resemble those of other conditions. The common cold and the flu can cause respiratory symptoms similar to allergies. Typically, allergy symptoms are associated with a specific time of year or exposure to an allergen.
Causes of allergies
Allergies result from an inappropriate or misguided reaction to foreign substances (usually harmless substances). Allergens are the substances that trigger allergies. Pollens are the allergens that cause hay fever, one of the most common types of allergic reaction.
A review of our Patient Comments indicated that many people with allergies have similar symptoms and signs. Oftentimes, an allergy attack began with itchy eyes followed by facial swelling, particularly of the eyes and lips. Some patients mentioned that the itchiness occurred all over their bodies, and sometimes they developed hives. Several people indicated that their symptoms felt flu-like, in that they experienced coughing, fatigue, and the sensation that they had a fever. Read on to learn more about allergy symptoms in our Patient Comments.
- Nasal Congestion
- Reddened Skin
- Runny Nose
- Scratchy Throat
- Shortness of Breath
- Swelling of the Throat
- Watery Eyes
Pictures, Images, Illustrations & Quizzes
10 Worst Cities for Spring Allergies With Pictures
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Allergies Quiz: Symptoms & Home Remedies
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Allergies: 10 Ways to Reduce Mold Allergies
WebMD shows you 10 ways to fight the fungus and reduce mold allergy symptoms from dust masks to bottles of bleach.
Allergies: Common Plants and Trees That Trigger Allergies
Find out more about which plants and trees might be producing pollen that is causing your itchy eyes and a runny nose.
Allergies: Myths and Facts About Seasonal Allergies
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Allergy: Life-Threatening Allergy Triggers
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Could I Be Allergic? Discover Your Allergy Triggers
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Home Allergy Quiz: Is Your Home Allergy-Proof?
Take this home allergy quiz and test your knowledge on allergens, dust mites, pollens and more to see how allergy-proof your home...
Managing Severe Allergies at School
Learn how to manage and be prepared for severe allergies at school. Discover how to protect you child from food allergies, insect...
Nasal Allergy Attack: Causes, Triggers, Treatments
Nasal allergies are a common problem that affects millions of people. An allergist can recommend the best allergy nasal sprays...
Nasal Irrigation: Natural Relief for Cold & Allergy Symptoms
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Out-of-Control Allergy Symptoms: Treatment Relief in Pictures
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Picture of Allergic Contact Dermatitis
A red, itchy, weepy reaction where the skin has come into contact with a substance that the immune system recognizes as foreign....
Picture of Allergic Contact Dermatitis (Arm)
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Picture of Allergic Contact Dermatitis (Tattoo)
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Picture of Allergic Reaction to Lipstick Tattoo
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Picture of Eye Allergies
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Picture of Tattoo Allergic Reaction
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Pictures of Allergy Relief Tips at Home: AC Filters, Electronic Air Cleaners, and More
Learn how a combination of medication, preventing allergens, and allergy relief products can reduce allergy symptoms and help you...
The Most Common Food Allergies for Kids and Adults
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Top 13 Ways to Tame Eye Allergies
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When Animal (Allergies) Attack: Pet Allergy Symptoms, Treatment
How do you control and relieve pet allergies? How do you prevent pet allergies? Learn dog and cat allergy symptoms, the cause of...
Examples of Medications for Allergy
- cetirizine (Zyrtec, Zyrtec Allergy, Zyrtec Hives)
- Claritin (loratadine) vs. Zyrtec (cetirizine)
- diphenhydramine, Benadryl
- Dymista (azelastine hydrochloride and fluticasone propionate)
- fexofenadine (Allegra, Mucinex Allergy)
- loratadine and pseudoephedrine (Alavert Allergy & Sinus, Claritin-D, Claritin-D 24 hour)
- loratadine, Claritin, Claritin RediTabs, Alavert, Claritin Hives Relief, Children's Claritin
- Ondansetron (Zofran) vs. promethazine (Phenergan)
- Vistaril (hydroxyzine) Side Effects, Warnings, and Interactions
- Xyzal (levocetirizine dihydrochloride)