Allergies

Allergies are your immune system’s overreaction to foreign substances. When you touch, inhale or eat something you’re allergic to, your body thinks it’s harmful and reacts to try to get rid of it. This can cause minor reactions like itching, sniffling and sneezing. But in some cases, allergic reactions can lead to life-threatening airway swelling and low blood pressure (anaphylaxis).

You can be allergic to almost anything — like pollen, animals, medications and food. Some people have allergies that are merely annoying. Others have to completely alter their lives to avoid reactions.

Types of allergies

Some common allergies include:

• Bee stings and other insect stings and bites
• Dust mites
• Foods
• Medications
• Molds
• Pets and other animals
• Poison ivy rashes and other contact dermatitis reactions
• Pollen (seasonal allergies)

Symptoms of allergies

Allergies can cause a range of symptoms, including:

• Skin rash or hives
• Itchy skin
• Sneezing
• Stuffy or runny nose
• Cough
• Wheezing
• Itchy, watery eyes
• Swelling of your face, lips, tongue or throat
• Difficulty breathing or swallowing
• Vomiting or diarrhea
• Low blood pressure

Symptoms often depend on how you’re exposed to an allergen. For instance, if you touch something you’re allergic to, you might get an itchy rash. If you’re allergic to pollen or pet dander, you usually get a runny nose or sneeze when you breathe them in. Food and drug allergies and bee stings are more likely to cause severe reactions, like airway swelling and vomiting.

How long can allergies last?

Your allergies will continue as long as you’re exposed to the allergen. Some start within minutes of exposure, while others don’t start until hours or days later. Once you’re no longer around allergens, your symptoms should go away after a few hours. Some allergies, like poison ivy rashes, can last for a few weeks.

What causes allergies?

Allergies happen when your immune system mistakenly identifies foreign proteins — in pollen, pet dander, medications, food or other substances — as something harmful (as if it were a virus or bacteria). Inhaling, eating or touching something you’re allergic to activates mechanisms meant to protect you and flush the allergen out of your system. This causes your symptoms, which can sometimes be life-threatening.

You generally have to be exposed to a substance more than once before you’ll react to it. The first time you’re exposed, your body sees it as foreign and creates antibodies to it (sensitization). The next time you’re exposed to the same substance, it activates the antibodies. This alerts your immune system to attack, triggering your symptoms.

Risk factors

You’re more likely to have allergies if you have:

• A biological parent with allergies
• Conditions like asthma or eczema (atopy)

How doctors diagnose allergies

A healthcare provider can diagnose allergies with a skin test or blood tests. To determine what allergens to test for, they’ll ask you about your symptoms and any possible allergens you could be exposed to, like through work or hobbies.

Depending on your suspected allergies, they might also recommend breathing tests, drug or food challenge tests, or a patch test. A patch test looks for a contact skin reaction that happens over a few days.

How are allergies treated?

Avoiding things you’re allergic to is your best bet to manage allergies. This is especially true if your allergies are likely to cause anaphylaxis.

But some common allergens can be hard to avoid. Your healthcare provider might recommend you take certain medications daily or get specific treatments regularly. These can reduce your symptoms or risk of a reaction. Depending on your allergies, options could include:

• Antihistamines like fexofenadine (Allegra®), loratadine (Claritin®) or cetirizine (Zyrtec®)
• Steroid nasal spray (Flonase® or Nasacort®)
• Leukotriene modifiers like montelukast
• Omalizumab (Xolair®) injections for food allergies or hives
• Allergy immunotherapy, like allergy shots, sublingual immunotherapy (SLIT) or oral immunotherapy (OIT)

If you have an allergy that could cause a severe reaction, your provider will recommend you carry an epinephrine auto-injector (EpiPen® or Auvi-Q®) to use at the first signs of a severe allergic reaction.

When should I see my healthcare provider?

Talk to a healthcare provider if you have symptoms of allergies and want to get to the bottom of what’s causing them. A primary care provider might refer you to a specialist, like an allergist or dermatologist, to get certain tests.

Go to the ER or call 911 if you experience:

• Swelling of your face, lips, tongue or throat
• Difficulty breathing
• Chest pain or tightness
• Hives all over your body
• Tingling hands, feet or lips
• Feeling weak, dizzy or faint
• Feeling of dread or impending doom

Can allergies be prevented?

You can’t really avoid developing allergies to begin with. To avoid reactions to known allergens, you can:

• Avoid touching or getting licked by animals you’re allergic to and change your clothes after you’ve been around them (don’t allow them in your bedroom or on your furniture, and don’t touch their toys)
• Regularly vacuum rugs, carpets and other surfaces to help remove dust, animal dander, pollen and other allergens
• Use high-efficiency particulate (HEPA) air filters to help remove allergens from the air around you
• Keep your windows closed during pollen season
• Change the filters on your HVAC system on their recommended schedule

If you have a food allergy, check food labels, keep allergen-free foods in your house, and only eat at restaurants where you know you can eat something that’s allergen-free.

What can I expect if I have allergies?

What to expect when you have allergies depends on what kind they are. Seasonal or pet allergies are generally more likely to cause irritating, but not life-threatening, reactions. Food and drug allergies and bee stings are more likely to cause serious reactions. You’ll probably need to carry an epinephrine injector if you have one of these allergies.

What can I do about allergies?

If you’re still having bothersome allergy symptoms even with treatment, you might get some relief with:

• Oral decongestants or saline rinses for nasal symptoms
• A cold washcloth or eye drops made for allergies to help relieve itchy eyes
• Showering and putting on fresh clothes to help remove lingering allergens on your body
• Hypoallergenic or fragrance-free lotions to help calm itchy rashes

Do allergies get worse with age?

Allergies can change with age. This can depend on how much (or how little) you’re exposed to an allergen, changes in your immune system and other factors.

Sometimes, existing allergies get worse, or allergies that seemed to have gone away can come back. Other times, existing allergies can get better over time — say, if you’re allergic to cats but you’re around them regularly anyway. Finally, some people can get new allergies as adults.