Allergies are a common health problem that affects many people around the world. About 30-40% of people today have one or more allergies, and the number of people with allergies has been increasing over the past 20 years. Common allergens include things like pollen, certain foods, pet hair, and house dust mites. Other types of allergies include drug, insect sting, latex, skin, and chemical allergies.

The World Health Organization (WHO) states that allergic rhinitis, also referred to as hay fever, and asthma are common allergic conditions affecting many individuals worldwide. Allergies can trigger these conditions, cause difficulty breathing, and impact the quality of life for those affected. They can also be costly to manage. Experts believe that factors such as air pollution and rising temperatures may worsen allergies in the years to come. These environmental changes can lead to increased pollen levels, more stinging insects, and greater mold growth, all of which can exacerbate allergic reactions.

Food allergy is another worldwide condition and is estimated to affect 2-10% of adults and children. Some of the most common food allergens are peanuts, tree nuts, eggs, milk, and fish. In many Western countries, the number of food allergies has been rising, while in some parts of Asia and Africa, food allergies are not as common.

An allergic reaction happens when something your body is allergic to, called an allergen, enters your body. This triggers a response from your immune system. The immune system makes special cells, called antibodies, to fight off what it thinks is a threat. When the allergen touches the antibodies, the body releases histamine and other substances, which cause the allergy symptoms.

These symptoms are like an alarm to your body, warning that something is wrong.

  • Sneezing helps clear your nose of things your body thinks are harmful. This is common in allergic conditions like hay fever or allergic rhinitis.
  • Nasal itching is a sign that something is irritating your nose.
  • Nasal congestion happens when there’s a buildup of mucus, inflammation, or growth of small tissues called polyps.
  • Nasal mucus is the sticky stuff in your nose that traps harmful particles. It can be thin or thick and may be clear or colored.
  • Nasal swelling happens when fluid from the blood vessels moves into the deeper skin layers, causing puffiness.
  • Eye itching is a sign that something is wrong in your eyes and causing irritation.
  • Eye redness happens when blood vessels in the eye get bigger, causing the eyes to look red.
  • Coughing clears your airways of mucus or particles, like allergens or germs.
  • Chest tightness feels like pressure in your chest and makes it hard to breathe. It happens when the airways are narrow, so the air doesn’t pass easily.
  • Shortness of breath is when it’s hard to inhale or exhale air, often seen in conditions like asthma.
  • Headaches can happen when mucus blocks your sinuses and causes pressure in your head.
  • Diarrhea is when food moves too quickly through your digestive system, often seen in food allergies and anaphylaxis.
  • Abdominal pain happens when your digestive system isn’t working right, and you may feel pain in your stomach.
  • Vomiting is your body’s way of getting rid of something harmful, like food allergens.
  • Wheezing is a whistling sound when breathing, which happens when your airways are narrowed, and it’s common in asthma.
  • Skin redness or rash is often a sign of atopic dermatitis or contact dermatitis, caused by inflamed blood vessels in your skin.
  • Skin itching is your body’s signal that something is wrong. It happens when nerve receptors in your skin get activated (like in eczema or contact dermatitis).

In serious cases, a severe allergy can cause anaphylaxis, which is a life-threatening reaction that needs immediate treatment.

Each allergic person reacts differently to different allergens, so it is important to understand what is specifically causing your allergies.

Common causes of environmental, food, and drug allergies include

  • Pollen, such as from trees, grasses, or weeds
  • House house dust mites
  • Cats and dogs
  • Stinging insects like bees and wasps
  • Molds
  • Foods
  • Medicine

Allergies come in two main types based on how they work. The first type is called IgE-mediated allergies, which is the type we talk about on this website. The second type is non-IgE-mediated allergies.

IgE-mediated Allergy

An IgE-mediated allergy makes special antibodies called IgE. These antibodies are specific to the substance that causes your allergy (like pollen or peanuts). The IgE antibodies attach to special cells in your body called mast cells, and this process is called sensitization. During the process of sensitization, you don’t feel any symptoms, but your body is getting ready to react next time it encounters the allergen.

Mast cells are found in areas like your skin, eyes, nose, mouth, throat, stomach, and gut. When your body comes in contact with the allergen again, these mast cells recognize it and act like they’re under attack. They release histamine and other chemicals to fight what they think is a threat. This is what causes allergy symptoms.

Non-IgE Mediated Allergy

Non-IgE-mediated allergies are different from the more common IgE-mediated allergies. They are less understood and happen when T-cells, a type of white blood cell, are involved. These allergies are connected to conditions like contact eczema (also called allergic contact dermatitis). While symptoms from IgE allergies show up quickly, non-IgE allergies can take 24-48 hours to appear after coming into contact with an allergen.

Allergic reactions can be different every time you come into contact with something you’re allergic to. Some reactions happen right away, while others might take longer to show up. There are two types of allergy reactions to know about.

Acute Response (Immediate Reaction)

This is the type of allergy reaction most people are familiar with. It happens within 15-30 minutes of contact with the allergen. During this time, the body releases chemicals like histamine, prostaglandins, and leukotrienes, which cause the body to react. For example, these chemicals can cause symptoms like sneezing, swelling, and mucus production in the respiratory system. These reactions can also cause a blocked nose and difficulty breathing, leading to symptoms like wheezing.

Late-Phase Response (Delayed Reaction)

This happens 4-6 hours after the first symptoms go away and can last for days or weeks. In this phase, the immune system causes inflammation and damage to tissues in the body. This can lead to more swelling, edema, and difficulty breathing in the lungs. This delayed reaction is why it can take time for symptoms to show up and worsen.

Do you sneeze every time you pet a cat? Do you get itchy hives if a bee or wasp stings you? If so, you might already know some things you’re allergic to. Sometimes, though, you might not know what’s causing your allergy symptoms. To find out for sure, you need to talk to a doctor who can look at your medical history, perform an exam, and do some allergy tests. Diagnosing allergies can be tricky because their symptoms can feel like those of other health problems. If needed, your doctor might send you to an allergy expert for more help.

Doctors diagnose allergies in 3 steps:

  1. Personal and Medical History

When you visit your doctor, they will ask you many questions to understand why you have certain symptoms. It’s a good idea to write down some information at home. Think about your family’s health history, the medicines you take, and your daily routines at home, school, or work. Note down when and where your symptoms happen. Do they occur during specific times of the year? Do you feel worse at night or during the day? Do your symptoms appear after being around animals? Are there certain times of the day when they happen? Does any food or drink seem to trigger them? This information will help your Doctors understand your condition better.

  1. Physical Exam

If your doctor thinks you might have an allergy, they will check your eyes, nose, ears, throat, chest, and skin during the exam. They may also check your lungs with a special pulmonary function test. Sometimes, you might need an X-ray of your lungs or sinuses to get more information.

  1. Tests to Identify Allergens

Doctors have different tests to help determine if you have allergies. Each person’s experience with these tests can be different, and no single test can tell if you have an allergy. These tests are just one way to help your doctors make a diagnosis.

Learn More about the tests Doctors use to diagnose allergies >

Managing allergies starts with avoiding the things that cause them, known as allergens. The best way to keep your allergies under control is to stay away from these triggers. A doctor can help you figure out which allergens you need to avoid based on your situation.

Medications can help control allergy symptoms, but they don’t cure allergies. If you can’t avoid allergens, there are medicines available that can relieve your symptoms. Decongestants and antihistamines are the most common allergy medicines. They can help with stuffy noses, runny noses, sneezing, and itching. Corticosteroids can reduce swelling in your nose and airways. While these treatments can help with symptoms, they won’t make allergies go away completely.

One way to possibly change how your immune system reacts to allergens is through allergen immunotherapy. This treatment can help you become less sensitive to triggers over time. Using both avoidance and medication can work together to lessen allergy symptoms.

Most allergic reactions are mild and might be annoying, but they usually aren’t serious. However, some people can experience a severe reaction called anaphylaxis, which can be life-threatening.

What is anaphylaxis?

Anaphylaxis is a serious allergic reaction that can be life-threatening. It can happen just seconds or minutes after you come into contact with something that you’re allergic to. The most common things that cause anaphylaxis are certain foods, insect stings, and some medications.

When you have an allergy, your immune system reacts strongly to the allergen by releasing chemicals that lead to symptoms. Normally, these symptoms show up in one part of your body. But for some people, anaphylaxis can affect many parts of the body all at once. During anaphylaxis, the chemicals released can cause a person to go into shock. This means that your blood pressure can drop quickly, and your airways can narrow, making it hard to breathe.

Signs and symptoms

Anaphylaxis is a serious allergic reaction that can happen very quickly, sometimes just seconds or minutes after you touch or eat something you’re allergic to.

Watch for these signs and symptoms; if two or more occur, seek medical attention immediately:

  • Skin reactions, like a rash, hives, or itching
  • Skin that looks flushed or pale
  • A warm feeling in your body
  • A lump sensation in your throat
  • Wheezing or trouble breathing, tightness in your throat, coughing, a hoarse voice, chest pain, trouble swallowing, and itchy feelings in your mouth or throat, as well as stuffy or congested nose
  • A weak and fast heartbeat
  • Nausea, vomiting, or diarrhea
  • Dizziness or lightheadedness
  • Headache
  • Feeling anxious
  • Low blood pressure
  • Passing out or losing consciousness

The most dangerous symptoms are low blood pressure, problems breathing, and losing consciousness, which can be very serious or even life-threatening. If you see any of these symptoms, especially after eating something, taking medicine, or getting stung by an insect, get medical help right away. DON’T WAIT!!!! Anaphylaxis needs emergency and immediate treatment with epinephrine.

Common causes of severe allergic reactions and anaphylaxis

Foods

Any food can cause an allergic reaction. Foods that cause the majority of anaphylaxis are peanuts, tree nuts (such as walnut, cashew, Brazil nut), shellfish, fish, milk, eggs and preservatives.

Stinging insects

Insect sting venom from, honeybees, wasps or yellow jackets, hornets and fire ants can cause severe and even deadly reactions in some people.

Medications

Common medications that cause anaphylaxis are antibiotics (such as penicillin) and anti-seizure medicines. Certain blood and blood products, radiocontrast dyes, pain medications and other drugs may also cause severe reactions.

What to Do After an Anaphylactic Reaction

If you experience anaphylaxis, it’s important to act quickly.

Steps to take:

  1. Use your epinephrine (epinephrine autoinjector or nasal spray) right away:
    • If you have an epinephrine autoinjector or nasal spray, use it right away, even if you’re not sure if it’s an emergency.
    • Epinephrine helps your body stop the allergic reaction and can save your life. It should be given into your thigh and stays there for 10 seconds.
  2. Call for help:
    • After using the epinephrine autoinjector or nasal spray, contact your doctor or emergency services, or have someone take you to the hospital. It’s important to get checked out by a doctor in many cases because a second reaction can occur, and you might need more treatment.
  3. Stay calm and wait for help:
    • If you can, try to stay calm and sit or lie down while waiting for help. Sometimes, anaphylaxis can cause dizziness or weakness, so it’s important to avoid standing up too quickly.
  4. Follow up with your doctor:
    • After the emergency is over, it’s important to see your doctor to discuss further treatment or changes to your allergy plan. Your doctor can help you figure out how to avoid future reactions.

Important to Remember:

  • Always carry two epinephrine autoinjectors or nasal sprays with you if you have severe allergies. This prepares you if a 2nd dose of epinephrine is needed to treat your symptoms.
  • Make sure family, friends, and teachers know how to use your epinephrine autoinjector or nasal spray and what to do if you have an allergic reaction or anaphylaxis.
  • Don’t wait to use your epinephrine autoinjector and nasal spray if you are experiencing anaphylaxis—using it early can make a big difference.
  • If you have allergies or asthma and have a family history of anaphylaxis, your risk for anaphylaxis is higher. Even if you or your child has had only a mild anaphylactic reaction in the past, there’s still a risk of more severe anaphylaxis.

Anaphylaxis Treatment

Epinephrine is the most important medicine for treating anaphylaxis, which is a serious allergic reaction. The faster someone gets epinephrine during an anaphylactic episode, the better their chances are to feel better and survive.

If someone has a severe reaction and stops breathing or their heart stops, a bystander or emergency medical team may perform CPR (cardiopulmonary resuscitation) to help them.

In addition to epinephrine, doctors might give other medications based on how serious the symptoms are. This could include:

– Antihistamines and cortisone through an IV to help reduce swelling in the airways and improve breathing.

– A beta-agonist, like albuterol, to help with breathing problems.

– Oxygen to help make breathing easier.

Epinephrine can be given by yourself using either an autoinjector or a nasal spray. The autoinjector looks like a pen and injects a dose of epinephrine when you press it against your thigh. The nasal spray is a small device that you spray into your nose. It’s important to know how and when to use epinephrine yourself, and make sure your family, friends, and teachers know how to help if you need it.

Always remember to refill your prescription when it runs out, and don’t let your epinephrine freeze (below 0°C). If you’re flying, you can take the autoinjector or nasal spray with you in your hand luggage. Since airport security might not know the rules, ask your doctor for a signed letter explaining that you need to carry it.

Allergy immunotherapy is a medical treatment designed to reduce or eliminate allergic reactions by desensitizing the body to specific allergens over time. It is often used for people with allergic rhinitis (hay fever), asthma, and certain other allergic conditions. The goal of immunotherapy is to change the way the immune system responds to allergens, making the body less sensitive to them.

How Allergy Immunotherapy Works:

In this treatment, you’re given small amounts of the allergen you’re allergic to, either through shots (called subcutaneous immunotherapy), or tablets or drops (called sublingual immunotherapy). The amount of allergen is slowly increased to help your immune system tolerate it. This helps your body get used to the allergen and stop reacting so strongly to it.

As treatment continues, your immune system makes fewer antibodies (the proteins that cause allergic reactions), which helps reduce symptoms like sneezing, itchy eyes, and stuffy noses.

Types of Allergy Immunotherapy:

  1. Subcutaneous Immunotherapy (SCIT):
    • This involves allergy shots that are given under the skin.
    • At first, you get shots once or twice a week, and over time, the visits become less frequent.
    • Treatment usually lasts about 3 to 5 years.
  2. Sublingual Immunotherapy (SLIT):
    • This involves taking tablets or drops with allergens, placed under your tongue.
    • You take these daily, often at home, and they are used for allergies to pollen, house dust mites, and pets.

Benefits of Allergy Immunotherapy

Allergy immunotherapy, also known as allergy shots or tablets, helps reduce or eliminate allergy symptoms by gradually desensitizing the body to the things that cause allergies. Here are some benefits:

  1. Long-term relief:
    • Allergy shots or tablets can provide long-lasting relief. After finishing treatment, many people find that they need less medicine and have fewer allergy symptoms.
  2. Better control over symptoms:
    • Immunotherapy can help control symptoms like sneezing, itching, runny nose, and itchy eyes. It can also make symptoms less severe when you are exposed to allergens.
  3. Reduces the need for medications:
    • Once you complete allergy immunotherapy, you may not need to take as many antihistamines or other allergy medicines.
  4. Helps prevent asthma:
    • For some people, allergy immunotherapy can help prevent allergies from turning into asthma or help improve symptoms if you already have asthma.
  5. Improves quality of life:
    • By reducing allergy symptoms, immunotherapy can make everyday activities like going outside or playing sports more enjoyable without worrying about constant sneezing or a stuffy nose.
  6. Safe and effective:
    • Allergy immunotherapy is a safe and effective treatment for many people, and it is approved by doctors to help reduce long-term allergy problems.

When is Allergy Immunotherapy Used?

Allergy immunotherapy is used when other treatments, like allergy pills or sprays, don’t work well enough. It’s often used in the following situations:

  1. Severe allergies:
    • If you have strong allergic reactions (like a runny nose, itchy eyes, or sneezing) that don’t go away with regular medicine, allergy immunotherapy can help reduce those symptoms.
  2. If you have multiple allergies:
    • When you are allergic to several things, like pollen, dust, pets, and mold, and it’s hard to keep the symptoms under control, immunotherapy might be a good option to treat them all at once.
  3. If you want to avoid long-term medicine:
    • If you are tired of taking allergy medicine every day, allergy immunotherapy can help you get rid of symptoms for good, so you don’t have to take medicine all the time.
  4. If you aave allergies that lead to asthma:
    • If your allergies cause you to have asthma, allergy immunotherapy can help prevent asthma or reduce asthma symptoms.
  5. If you want long-term relief:
    • If you want long-lasting relief from your allergies without always needing medication, allergy immunotherapy is a good option because it can work for years after treatment.

Possible Side Effects of Allergy Immunotherapy:

Some people may have mild reactions after getting a shot or eye drops. This can include things like redness, swelling, or itching at the spot where they got it. In very rare cases, some people can have a serious allergic reaction called anaphylaxis, especially after getting an allergy shot.

Content Reviewed by GAAPP’s Scientific and Advisory Panel