An allergy is an immune system response to a foreign substance, or allergen, that’s not typically harmful to the body. Symptoms and treatments may vary depending on the type of allergy you have.

The immune system is responsible for keeping you healthy by fighting harmful pathogens.

It does this by creating antibodiesTrusted Source called immunoglobulin. There are several types of immunoglobulins, which fight against possible agents like bacteria, viruses, parasites, and chemicals. Immunoglobin E (IgE) is a type that responds to certain substances and causes an allergic reaction.

Allergic reactions may involve a variety of symptoms, ranging from mild inflammation to life threatening situations.

According to the Centers for Disease Control and Prevention (CDC), 1 in 3 peopleTrusted Source have an allergy in the United States.

Keep reading to learn more about the types, symptoms, and causes of allergies, as well as how to treat them.

When to get immediate medical attention
Sometimes, allergic reactions may cause symptoms that could be life threatening, known as anaphylaxis.

If you or someone you know suddenly experiences any of the following symptoms, call 911 or get immediate medical attention:

swelling in the face, throat, and tongue
dizziness, confusion, fainting
difficulty breathing, swallowing, and speaking
wheezing or coughing
skin discoloration, such as blue, pale, or gray tongue
If you or the person has an epinephrine autoinjector, use it immediately. The shot counters allergic reactions until medical help arrives and could be lifesaving.

Learn more about what to do if someone has an allergic reaction.

Types of allergies
There are several types of allergies, according to Allergy UK. These include:

food allergies
hayfever (allergic rhinitis)
asthma
atopic dermatitis (eczema)
skin allergies
medication allergies
insect bite allergies
Symptoms of allergies
Symptoms of allergies may depend on several factors, such as the type and severity of your allergy.

According to the American College of Allergy, Asthma, and Immunology (ACAAI), common allergy symptoms may include:

congestion
runny nose
sneezing
coughing
fatigue
headaches
rashes, such as hives
nausea
vomiting
fever
wheezing
difficulty breathing
Learn more about the most common allergy symptoms.

Skin allergy symptoms
Certain skin symptoms may indicate an allergic reaction.

For instance, you may experience tingling in your mouth after eating a food you’re allergic to. Or, you may experience an allergic reaction if your skin comes into direct contact with an allergen, known as contact dermatitis.

Symptoms of skin allergies may include:

rashes
hives
swollen, watery, or puffy eyes
itching
burning
Learn more about allergy symptoms and what might cause them.

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Causes of allergies
It’s still unclear why the immune system causes an allergic reaction when a normally harmless foreign substance enters the body.

However, researchers have identified several factors that may contribute to allergies, including:

older age
genetics
hormonal changes, especially in people assigned female at birth
immunological factors, such as weakened immune system
gut microbiome changes
having other allergies, such as atopic dermatitis
Several common allergens have also been identified, including foods, medications, and environmental irritants. The cause of allergies may depend on how you come into contact with it:

Ingestion: Foods like nuts, cow’s milk, sesame, fish, tree nuts, and shellfish may cause allergies. Some oral medications like penicillin may also trigger a reaction.
Inhaling: Several environmental irritants, such as pollution, pet dander, mold, pollen, and dust mites, can trigger allergies.
Direct contact: Some allergies are caused by direct contact with allergens, such as insect stings, the sun, certain plants, latex, and certain metals.

How allergies are diagnosed
A doctor will first ask about your symptoms and perform a physical exam.

They may ask about anything unusual you may have eaten recently and any substances you may have come in contact with. For example, if you have a rash on your hands, they may ask if you put on latex gloves recently.

To confirm an allergy, they may order several tests, including:

Blood test: This can help detect the presence of IgE, which are cells that react to allergens.
Skin prick test: Small amounts of an allergen are pricked, brushed, or scratched against your skin to see if there’s an allergic reaction.
Learn more about allergy testing and diagnosis.

Allergy treatments
Avoiding the allergen that triggers the reaction is the best way to prevent allergies. If that’s not possible, there are treatment options available.

Medication
Allergy treatment usually includes over-the-counter or prescription medications, which are available as nasal sprays, pills, liquids, and topical ointments.

Some allergy medications may include:

antihistamines, such as diphenhydramine (Benadryl), loratadine (Claritin), and cetirizine (Zyrtec)
corticosteroids
decongestants (Afrin, Suphedrine PE, Sudafed)
mast cell stabilizers, which stop mast cells from releasing histamine
It’s important to work with a healthcare professional to develop the best management plan for your allergies.

Immunotherapy
Immunotherapy is a treatment that involves administering small doses of an allergen to help your body become used to it over time.

There are two types of immunotherapy:

Injections: This involves several injections over a few years. It’s most helpful for allergens like pollen, pet dander, insect stings, and asthma.
Sublingual immunotherapy (SLIT): This involves placing small doses of allergens under your tongue. It’s best for asthma and nasal allergies, such as dust mites, ragweed, and grass.
Successful immunotherapy can prevent allergy symptoms from returning.

Emergency epinephrine
If you have a severe, life threatening allergy, you’ll most likely have to carry an emergency epinephrine autoinjector. This is the first-line treatment for anaphylaxis.

This shot counters allergic reactions until medical help arrives. Common brands of this treatment include:

Epipen
Twinject
Emerade
Jext
Natural remedies
Several natural remedies and supplements could help relieve allergy symptoms. These may include:

saline irrigation
cleaning the air filters in your home
using a humidifier
trying essential oils
modifying your diet
It’s important to note that limited research supports the efficacy of these natural remedies. They should be used alongside medical treatments, such as medication and immunotherapy.

Some home remedies may also trigger allergy symptoms in some people. For instance, some dried teas use flowers and plants closely related to plants that might be causing you to sneeze.

Learn more about 15 natural remedies for allergies.

Preventing symptoms
There’s no way to prevent allergies from developing, but there are ways to prevent symptoms.

The best way to prevent allergy symptoms is to avoid the allergens that trigger them.

Other tips to prevent allergies include:

following your allergy treatment plan, such as taking medications
trying an elimination diet
reading food labels
asking questions about ingredients when dining out
installing proper air filters in your home
regularly dusting your home
Learn more about how to prevent allergic reactions.

Complications of allergies
The most severe complication of allergies is anaphylaxis.

If not treated immediately, anaphylaxis may lead to death in less than 5 minutesTrusted Source.

Allergies and allergy treatments may lead to complications that affect your heart, circulation, and breathing. For instance, people with heart disease are at a greater risk of heart attack.

If you have allergies, speak with a healthcare professional about potential complications. They could help develop the best management plan for you.

Allergies vs. other conditions
Allergies may be associated with other conditions or cause similar symptoms.

Asthma and allergies
Asthma is a common respiratory condition that can make breathing more difficult and narrow the air passageways in the lungs.

Allergies are the most common asthma trigger, according to the Allergy and Asthma Foundation of America.

Allergic asthma is when these conditions occur together.

Allergies vs. cold
Allergies and the common cold may have similar symptoms, such as runny nose, headache, and coughing.

However, some additional signs and symptoms may help you distinguish between them. For instance, allergies may cause skin rashes and itchy eyes, while the common cold can lead to body aches and even fever.

The common cold may last up to 2 weeks, while allergies like hay fever could last a few months.

Learn more about the differences between allergies and the common cold.

Hay fever cough vs. chronic cough
Hay fever may produce symptoms that include sneezing, itchy eyes, and coughing.

Chronic cough is a cough that lasts more than 8 weeks.

Hay fever cough is usually temporary because it’s typically a seasonal allergy. However, sometimes hay fever may cause a dry cough that lasts longer than 3 weeks.

Allergies and bronchitis
Bronchitis is inflammation of the lungs, typically caused by a viral infection, such as influenza or the common cold.

Acute bronchitis may last up to 3 weeksTrusted Source, but chronic bronchitis can linger for months and return frequently.

Bronchitis may result from common allergens, such as pollen, cigarette smoke, and perfume, among others.

Allergies and children
Your child may have an allergy if they experience frequent symptoms like coughing, sneezing, skin rashes, and nausea, according to the ACAAI.

According to the CDC, 1 in 4 childrenTrusted Source in the United States experienced an allergy in 2021.

The three most common allergies in children are:

hay fever
skin allergies
food allergies, with peanuts and cow’s milk being the two most common
Frequently asked questions
What are the most common allergy symptoms?
Common allergy symptoms include itchy eyes, sneezing, facial tenderness, headache, fatigue, difficulty breathing, wheezing, dizziness, lightheadedness, and nausea, among others.

What are the 9 major food allergies?
The 9 most common food allergies include cow’s milk, sesame, eggs, fish, wheat, shellfish, soy, peanuts, and tree nuts.

How to help with allergies?
Treatment for allergies may include medications like antihistamines, decongestants, and epinephrine autoinjectors, as well as immunotherapy and home remedies.

Takeaway
Allergies are common and don’t have life threatening consequences for most people.

However, if you’re at risk of anaphylaxis, it’s important to carry an epinephrine autoinjector and use it immediately if you experience allergy symptoms. This could be lifesaving.

Most allergies are manageable with avoidance, medications, and lifestyle changes. Working with a doctor can help reduce major complications and make life more enjoyable.