Allergies: Symptoms, Causes, Diagnosis, and Treatment

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.

Allergy Types

Skin allergy

Skin allergies are triggered by allergens, such as:

• Latex
• Pet dander
• Poison ivy
• Plant pollen
• Sunlight
• Water
• Food
• Bug venom or poop

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:

• Dust mites, a very common indoor allergen
• Cockroaches
• Mold
• Pollen
• Pet fur, feathers, and dander

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:

• Bahia
• Bermuda
• Fescue
• Johnson
• Kentucky blue
• Timothy

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:

• Burning bush
• Cocklebur
• Lamb's-quarters
• Mugwort
• Pigweed
• Russian thistle
• Sagebrush
• Tumbleweed

 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:

• Eggs
• Milk and dairy
• Peanuts
• Tree nuts, such as almonds, cashews, walnuts, and pine nuts
• Fish
• Shellfish, such as crab, lobster, and shrimp
• Wheat
• Soy
• Sesame (including tahini)

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:

• Penicillin and related antibiotics (this is the most common drug allergy)
• Sulfonamide antibiotics (also called sulfa drugs)
• Anticonvulsants
• NSAIDS such as aspirin and ibuprofen
• Chemotherapy drugs

Allergy Risk Factors

You may be more likely to have allergies if:

• Anyone in your family has asthma, allergies, or eczema
• You have asthma or eczema
• You're a child

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.

Allergy Symptoms

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:

• Rash
• Itch
• Redness
• Swelling
• Bumps
• Flaky skin
• Cracked skin

Animal allergies cause symptoms such as:

• Runny or stuffy nose
• Face pain due to a stuffy nose
• Sneezing
• Watery, red, and itchy eyes
• Cough, chest tightness, shortness of breath, and wheezing
• Skin rash or hives

Bug allergy

Symptoms of cockroach allergy include:

• Coughing or wheezing
• Stuffy nose
• Sinus infection
• Ear infection
• Skin rash

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

• Hives, itching, and swelling in places other than the sting site
• Stomach cramps, vomiting, or severe nausea or diarrhea
• Tightness in your chest or trouble breathing
• Hoarse voice, swelling of your tongue or throat, or difficulty swallowing

Dust allergy symptoms include:

• Sneezing
• Runny or stuffy nose
• Red, itchy, and watery eyes
• Itchy skin
• Wheezing, coughing, shortness of breath

Food allergysymptoms

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:

• Vomiting, stomach cramps
• Hives
• Shortness of breath
• Wheezing
• Repeated cough
• Hoarse voice, tight throat, trouble swallowing
• Swelling of the tongue (affecting your ability to talk or breathe)
• Pale or blue-colored skin
• Dizziness or feeling faint
• Weak pulse
• Symptoms of shock, like heart palpitations or agitation
• Anaphylaxis, the symptoms of which can include rash, vomiting, trouble breathing, and dizziness

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.

Allergy Symptoms in Kids

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

• Stuffy and/or runny nose
• Sneezing
• Itchy nose
• Itching in their ears or the roof of their mouth
• Red, itchy, watery eyes
• Red, itchy, dry skin
• Hives or itchy welts on the skin
• Rash
• Asthma symptoms, such as shortness of breath, wheezing, or coughing
• Anaphylaxis

Allergy Symptoms Severity

Mild allergy symptoms

These include:

• Rash
• Itching in one area of your body
• Congestion

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:

• Widespread itching, swelling, or hives
• Difficulty breathing, tightness in your throat, or hoarse voice
• Nausea, vomiting, or abdominal pain

When to See a Doctor

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.

Allergy Diagnosis

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:

• Ask about your health and whether you have family members with asthma or allergies

• Ask about your symptoms

• Do a physical exam

• Run allergy tests

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.

Allergy Treatment

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.

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

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.

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:

• Saltwater solution, or saline, to rinse your sinuses and nose. This can relieve mild congestion, loosen mucus, and prevent crusting. They can soothe your nose and help with nosebleeds from blowing your nose a lot.
• Neti pots. These look like little teapots. You use the spout to pour diluted salt water into your nose to flush out mucus and moisten the tissues in your sinuses. Don't use plain water because it can irritate your tissues. Always use sterile water to make the saltwater solution. Wash your neti pot well and dry it with a paper towel or let it air dry completely between uses.
• Artificial tears. These can help relieve itchy, dry, watery, and red eyes.

Allergy Home Remedies

Some nondrug remedies that can help with symptoms include:

• Saltwater solution, or saline. You can use this as a nasal spray to rinse out your sinuses and nose. It helps relieve mild congestion, loosen mucus, and prevent crusting. It can soothe your nose and help with nosebleeds you get from blowing your nose a lot.
• Neti pots. These look like little teapots. You use the spout to pour diluted salt water into your nose to help flush out mucus and moisten the tissues in your sinuses. Don't use plain water, which can irritate your tissues. Always use distilled or sterile water to make the saltwater solution. After use, wash your neti pot well and dry it with a paper towel or let it air dry completely.
• Artificial tears. These can help relieve itchy, dry, watery, and red eyes.

Allergy Complications

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

• Anaphylaxis. The worse your allergies, the higher your risk for this type of serious reaction.
• Asthma. Another immune system reaction that makes it hard to breathe. If you have asthma, an allergic reaction can trigger an attack.
• Sinusitis (inflammation of the tissues in your sinuses): It can result when your sinuses try to flush out allergens.
• Ear or lung infections: These happen when tissues in those areas get inflamed and swell due to allergies.

Living With Allergies

Allergy prevention

In general, experts recommend that you:

• Know what triggers your allergies and avoid these allergens as much as possible. An allergy journal or diary can help with this. In your diary, track what you do and what you eat, as well as when symptoms happen and what seems to help.
• Take your medicines as prescribed.
• If you have epinephrine auto-injectors, always keep them with you.
• If you've ever had a severe allergic reaction, wear a medical alert bracelet or necklace.
• Have an emergency action plan in case you have a severe allergic reaction.

 To help reduce the levels of allergens in your home:

• Have a weekly cleaning routine that includes damp-mopping hard floors and vacuuming carpets. If you're the one with allergies, wear a dusk mask while you do this or have someone else do it. If possible, leave for a few hours afterward to avoid allergens you’ve stirred up. Use a vacuum cleaner with a small-particle or high-efficiency particulate air (HEPA) filter. Use a damp cloth to clean surfaces where dust may settle, the tops of the doors and window frames.
• Keep your house between 68 F and 72 F and keep the humidity at 50% or lower. Heat and humidity will make dust mites and mold worse. Clean or replace small-particle filters in your central heat and air systems at least once a month.
• Remove dust-collecting items such as knickknacks, ornaments, books, and magazines. Store toys, games, and stuffed animals in plastic bins to keep them from getting dusty.
• Control cockroaches and mice in your house with traps you buy from the hardware store or hire an exterminator. Thoroughly clean hard surfaces where cockroaches or mice may have been.
• Close doors and windows during warm weather and allergy season and use an air conditioner and/or a humidifier to prevent mold. Check your roof and ceilings for leaks. Wash anything contaminated with mold with a 5% chlorine solution. Wear a mask.
• Clean sheets, pillowcases, and blankets at least once a week with hot (at least 130 F) water. Use dust mite covers on pillows, mattresses, and box springs.
• Don't let anyone smoke inside.

What can I do to protect myself from outdoor allergens?

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

• Avoid going out when allergens are at their peak, usually between 10 a.m. and 4 p.m.
• Check the allergy forecast (download an allergy app or visit a weather website that tracks allergens). Stay indoors when pollen and mold counts are high or the wind is gusting, which could kick up dust and pollen.
• Consider wearing a face mask to limit how much pollen you breathe in.
• Wear a baseball cap during pollen season, and leave it at the door when you come inside.
• Avoid tracking pollen in your home by leaving your shoes at the door, changing your clothes, and showering and washing your hair immediately after going inside. Pets can bring in pollen, too. So keep your cats or dogs out of the bedroom.
• Wear sunglasses to protect your eyes from pollen.
• Roll up the car windows and use the air conditioner when you drive.
• Have someone else do the yard work.