Symptoms of an Allergy (original) (raw)

Allergies are when your immune system overreacts to something called an allergen. An allergen is a foreign substance that's not harmful to most people, such as pollen or pet dander (skin cells from animals with fur or feathers). But when you have allergies, your immune system tries to fight it off as it would a germ or virus.

When this happens, your body makes a protein called an antibody to fight the allergen. This leads to symptoms, such as sneezing, itching, hives, and shortness of breath. These symptoms are usually mild. But allergies can sometimes cause a serious reaction called anaphylaxis (pronounced a-nuh-fuh-lak-suhs), which is potentially life-threatening.

When is allergy season?

In many places in the U.S., there are two allergy seasons: spring and fall. Allergies that you get at similar times each year (seasonal allergies) are usually caused by pollen from trees, grasses, and weeds. Most trees release pollen in the spring, followed by grasses in late spring and early summer, and weeds follow in late summer and early fall.

Sometimes, seasonal allergies overlap, especially when trees release their pollen early or when a rainy spring causes more plants and molds to grow. So you may have one long allergy season in a year, depending on where you live, what plants grow near you, and what triggers your allergies.

What is an allergen?

An allergenis a substance that triggers an allergic reaction. The most common allergens include:

When you come into contact with an allergen, your immune system creates an antibody. The antibody serves as a tag that your immune system attaches to things it sees as dangerous.

When you come across that allergen again, your immune system takes action. The antibodies recognize it, and turn on mast cells. Mast cells are like watchers that live in your skin, nose, eyes, and digestive system. They let your immune system know when you've been invaded by foreign substances such as viruses and bacteria.

The mast cells then release chemicals, such as histamines, cytokines, and leukotrienes, that cause your allergy symptoms.

Your symptoms will depend on how much of the antigen you came in contact with and where it entered your body. For instance, if you breathe it in, you may have an itchy, runny, or stuffy nose and you may wheeze and cough. If it comes in through your eyes, you may have itchy, red, and watery eyes. If it enters through your skin, you may have a rash.

If the allergen enters your body through a food you ate or a medicine you took, you may vomit or have diarrhea, and you may also be at a higher risk of anaphylaxis. Certain foods, such as peanuts, tree nuts, and shellfish, are more likely to cause anaphylaxis.

Skin allergy

Skin allergies are triggered by allergens, such as:

Animal allergy

If you are allergic to animals, it is usually caused by proteins that animals make in their fur, skin, pee, and spit.

Insect allergy

Insect allergies can come from cockroaches or bug venom. Proteins in the poop, spit, or body parts of cockroaches can be allergens. So can proteins in venom from the stings of bugs such as honeybees, yellow jackets, hornets, wasps, and fire ants.

Dust allergy

Dust allergy can be caused by a number of allergens that make up house dust. These allergens include:

Seasonal allergy

Spring allergies are often caused by tree pollen. Many different trees make pollen that can cause allergy symptoms.

Summer allergies are often caused by grass pollen. Most grasses don't cause allergy symptoms, but some common grass pollens that can trigger allergies include:

Fall allergies are usually caused by ragweed pollen. Ragweed is a wild plant that grows everywhere in the U.S., especially in the Midwest and on the East Coast. Other plant pollens that may trigger fall allergies include:

Food allergy

About 4%-6% of kids and 4% of adults have some form of food allergy. Any food can cause a reaction, but most food allergies are caused by nine types of food:

Wheat (gluten) allergy is also common in children, but most (about 65%) of the kids outgrow it by the time they're 12.

You might hear about alcohol allergy, but this term is a bit misleading. Alcohol intolerance is a genetic condition in which your body can't break down alcohol very well. It's not really an allergy. Some people may have an allergic reaction to the grains (such as corn, wheat, or rye) used to make the alcohol. Others may have an intolerance to chemicals or preservatives, such as a type of wine preservative called sulfites.

Drug allergy

Drug allergies are usually caused by:

You may be more likely to have allergies if:

You may also be more likely to develop a new allergy if you are exposed to an allergen right after you've been sick or during pregnancy.

No matter what you're allergic to, the symptoms can be similar. Here's a breakdown of common symptoms by allergy type.

Common symptoms of skin allergies include:

Animal allergies cause symptoms such as:

Bug allergy

Symptoms of cockroach allergy include:

Symptoms that you're allergic to a bug's sting include:

Dust allergy symptoms include:

Food allergy symptoms

These symptoms may affect any part of your body, including your skin, digestive system, heart, blood vessels, or lungs. You may get one or more of the following:

Most food allergy symptoms show up within 2 hours of eating and sometimes start within minutes. In rare cases, symptoms may begin after 4-6 hours, usually in kids who get eczema as a symptom.

One very serious food allergy is called food protein-induced enterocolitis syndrome (FPIES). This is rare, and it mostly happens in babies who try cow's milk, soy, or some grains for the first time. Within 2-6 hours, they can have repeated vomiting and sometimes bloody diarrhea. Babies can get dehydrated fast, so this is an emergency. They need to go to the ER for IV fluids and other medicines.

Drug allergy symptoms

Drug reactions can occur in any part of your body. You may be able to take a drug a couple of times with no reaction. Symptoms include:

Allergic reactions can happen anywhere in your child's body. Whatever their age, allergic reactions may cause the following symptoms:

Mild allergy symptoms

These include:

Mild allergic reactions don't spread to other parts of your body.

Moderate allergy symptoms

Moderate allergic reactions include symptoms that spread to other parts of your body, including:

Anaphylaxis

Anaphylaxis is sudden and usually involves more than one part of your body. For instance, you may have both hives and swelling of your lips or tongue. It's more likely with food, drug, or bug sting allergies. It's possible to develop a severe allergic reaction to something you only had a mild reaction to before.

These symptoms can go from mild to serious within minutes. Serious symptoms include:

If you're having a severe allergic reaction (anaphylaxis), you need emergency medical help. If you have an epinephrine auto-injector pen, give yourself a shot right away and call 911. Tell the dispatcher that you've taken epinephrine for an allergic reaction. Even if that helps you feel better, you need to see a doctor immediately. Sometimes, the reaction will happen again and you'll need more epinephrine or other treatments.

If you've had a serious allergy attack or anysymptoms of anaphylaxis in the past, make an appointment with your doctor. You need long-term help managing your condition, including a prescription for an epinephrine auto-injector that you'll carry with you at all times. You may also want to see an allergist (a doctor who specializes in allergies) or immunologist (who specializes in immune system issues).

If you have symptoms you think are caused by an allergy and over-the-counter (OTC) medicines don't help, see your doctor. If you have any symptoms after starting a new medicine, immediately call the doctor who prescribed it.

If your allergy symptoms don't respond to OTC medications, or if you think you might have a food allergy, you'll need to visit an allergist. To diagnose allergies, your allergist will likely:

Allergy tests

Skin tests. The most common way to test for allergies is a skin test. That's because it gives the fastest, most accurate results.

Some medicines can get in the way of the tests. Ask your doctor whether you need to stop taking any medicationbefore the test.

The test that allergists use most often is called a skin prick test. A doctor or nurse will put a tiny drop of an allergen on your skin, usually on the inside of your arm or on your back.

Next, they'll prick your skin or make a small scratch on the surface through the drop to let the allergen get underneath. The skin prick won't make you bleed. You'll feel it, but it shouldn't hurt.

The doctor will probably test several allergens at the same time. If one of the areas swells up, itches, or gets red like a mosquito bite, it means you're sensitive to that allergen. It usually takes about 15 minutes to find out.

Some doctors use a small needle to put the allergen under the first few layers of your skin. This is called an intradermal skin test. Your doctor may use this test if your skin prick test is negative but they haven't ruled out allergies. They may also do it if they think you have a drug or bug venom allergy.

When the test is over, the doctor or nurse will clean your skin and put some cream on it to help with any itching. Any swelling from a reaction usually goes away within 30 minutes to a few hours.

**Blood tests.**If you take any medicines that could affect allergy test results, have sensitive skin, or have had a bad reaction to a skin test, your doctor might do a blood test instead. They may also test kids using a blood test.

During the test, a sample of your blood is sent to a lab, and the lab adds the allergen or allergens to your blood sample. They then measure the amount of antibodies your blood makes against the allergen. This is usually more expensive than a skin test, and it's also less accurate.

Food allergy testing. If your doctor thinks you might be allergic to a certain food or foods, they may ask you to stop eating them to see if that helps. This is called an elimination diet.

You'll cut out those foods for 2-4 weeks and see if you have any allergy symptoms during that time. If not, you'll start eating the foods again to see if your symptoms come back. If they do, there's a good chance you're allergic to those foods.

Your doctor also might ask you to do something called an oral food challenge. This should only be done in a medical office by an allergist.

Your doctor will give you very small amounts of the food you may be allergic to and watch for symptoms. If you don't have any, they'll slowly give you larger doses. If you start to have symptoms, they'll stop the test.

The most common signs are hives or a flushed feeling. If that happens, they'll give you medicine to make you feel better. If you don't have a reaction, your doctor will rule out an allergy to that food.

Immunotherapy

Immunotherapy is a treatment to prevent allergic reactions. There are two kinds: allergy shots and sublingual immunotherapy (SLIT). During immunotherapy, your doctor gives you a small amount of an allergen you react to. They slowly increase the amount you get until you become less sensitive to it. This reduces your symptoms when you come across that allergen again.

Allergy shots (subcutaneous immunotherapy or SCIT). Allergy shots are the most common form of immunotherapy doctors prescribe, and they work best. They can change your immune system and prevent you from getting new allergies and developing asthma. Shots are fairly safe. But there's a small chance you can have a reaction to them, so your doctor will watch you in their office after you get one.

Shots work well for allergies to plants, mold, house dust, animal dander, and bug stings. However, shots don't seem to work as well for allergies to food, medicines, or feathers. They may not help if you get hives or eczema. You usually get allergy shots once a week for about 7 months, then once every 2 weeks. Eventually, you'll only need one every 4 weeks. The entire process may take 3-5 years.

Sublingual immunotherapy (SLIT). SLIT doesn't use injections. Instead, your doctor gives you small doses of an allergen in a tablet under your tongue. The tablets dissolve for 1-2 minutes and then you swallow. You may need to take them every day, or you may take them every 3 days or so. For lasting effect, you may need treatment for 3-5 years.

Tablets are available for dust mites, grass, and ragweed. SLIT may help kids who have eczema because of allergies. Researchers are also studying SLIT as a possible treatment for food allergies, but this research is in an early stage. One medicine, peanut allergen extract (Palforzia), is available in the U.S. to treat peanut allergies.

Allergy medicine

Several types of medications can help relieve the symptoms of allergies**.**

Steroids. Steroids, known medically as corticosteroids, can reduce swelling and redness from allergies.

They prevent and treat nasal stuffiness, sneezing, and itchy, runny nose due to seasonal or year-round allergies. They can also decrease inflammation and swelling from other types of allergic reactions.

Steroids are available in various forms:

In addition to steroid medications, your doctor may prescribe additional types of medications to help combat your allergic symptoms.

Steroids work well, but you must take them regularly, often daily—even when you don't have symptoms. It may take 1-2 weeks of regular use before you notice the full effect.

Examples of steroids:

Antihistamines. Antihistamines have been used for years to treat allergy symptoms. They block histamine, which causes redness, swelling, and itching.

You can take them as pills, liquids, nasal sprays, or eye drops. OTC antihistamine eye drops can relieve red itchy eyes, while nasal sprays can be used to treat symptoms of seasonal or year-round allergies.

Some antihistamines can make you drowsy. Take care if you take these and need to drive or do other activities where you need to be alert. Other options, such as “nondrowsy” OTC decongestant pills, are less likely to have this effect.

You can take antihistamines as:

Decongestants. Decongestants relieve a stuffy nose and are often prescribed along with antihistamines for allergies. They work by shrinking your swollen nasal tissues and blood vessels. This temporarily relieves symptoms such as congestion, runny nose, and redness. Doctors don't recommend these for people with high blood pressure, heart disease, glaucoma, or hyperthyroidism (overactive thyroid).

Decongestants can come as nose sprays, eye drops, liquids, and pills.

You should use nose spray and eye drop decongestants for only a few days at a time because long-term use can make your symptoms worse. Pills and liquid decongestants can safely be taken longer.

Many are available without a prescription. You can buy them as:

Mast cell stabilizers. Mast cell stabilizers treat mild to moderate inflammation. They prevent the release of histamine from mast cells, which make and store this substance. Some of these drugs also have anti-inflammatory effects, but they don't usually work as well as steroids. Your doctor may prescribe them when antihistamines don't work or give you unacceptable side effects.

As with many drugs, it may take several weeks before you feel the full effects.

Mast cell stabilizers include:

Leukotriene modifiers. Leukotriene modifiers treat asthma and nasal allergy symptoms. They block the effects of leukotrienes, chemicals your body produces in response to an allergen. They can be prescribed along with other drugs.

They're available only with a prescription and come as pills, chewable tablets, and oral granules.

The only leukotriene modifier that has FDA approval to treat nasal allergies is montelukast (Singulair). Zafirlukast (Accolate) and zileuton (Zyflo) are also FDA-approved to treat asthma.

Combination allergy drugs. Some allergy drugs contain both an antihistamine and a decongestant to relieve multiple allergy symptoms. Other drugs have several effects aside from blocking the effects of histamine, such as preventing mast cells from releasing other allergy-inducing chemicals.

Examples of combination allergy medicines:

Anticholinergic nasal sprays. The drug ipratropium bromide (Atrovent) can help with a runny nose. It works by blocking a chemical called acetylcholine, which causes cells in your nose to make mucus.

Biologics. These medicines stop certain reactions in your immune system. You take these medicines as a shot, usually using an auto-injector. Your doctor may prescribe them when other medicines don't work. Some examples include:

Emergency epinephrine shots. Epinephrine shots are the most important treatment for a severe allergic reaction (anaphylaxis). You inject them with an auto-injector pen. You may need to carry two with you at all times if you've had any severe allergic reaction, but especially if you're allergic to foods or bug stings. Different brands work differently, so your doctor will train you on how to use your auto-injector. Make sure you replace your emergency epinephrine before the expiration date.

If you have a prescription for emergency epinephrine shots and think you're having an allergic reaction, use your shot immediately. Then call 911 and get to the ER right away. It's hard to tell how serious the reaction will be and you may need more than one shot to see an effect. You may also need other medicines to help your body get through the reaction.

Other OTC products that can help with symptoms include:

Some nondrug remedies that can help with symptoms include:

Having allergies increases your risk of developing these other medical problems:

Allergy prevention

In general, experts recommend that you:

To help reduce the levels of allergens in your home:

What can I do to protect myself from outdoor allergens?

You don’t have to stay indoors round the clock. Take these precautions: