How Do You Know If You Have Allergies?

It can sometimes be difficult to tell the difference between allergies and a cold, or other illnesses that cause similar symptoms. This is especially true if your allergy symptoms are mild. Though symptoms can vary, if you have itchy, watery eyes, and a runny nose, it's likely that you have allergies. In this article, we'll discuss allergy symptoms and their diagnosis and treatment.

Allergy Types - Illustration by Jiaqi Zhou

Verywell / Jiaqi Zhou

What Are Allergies?

Allergies are the ways your body responds to substances it sees as harmful. However, these substances are often harmless. For example, some people may sneeze and have watery eyes when they come in contact with pollen. The pollen, which causes your body to react in that way, is an allergen. 

During allergies, your immune system produces antibodies called Immunoglobulin E (IgE) that tag a harmless allergen as harmful. When you come across an allergen, your immune system then inflames different parts of your body like your skin, sinuses, and airway.


Your immune system keeps an eye out for an allergen so that it can release antibodies when it detects it again. These antibodies release chemicals like histamine, which cause allergic reactions. 

Common allergens include:

  • Grass and tree pollen
  • Pet dander, tiny flakes of skin or hair
  • Dust mites
  • Mold
  • Food, such as peanuts and tree nuts, wheat, soy, fish, shellfish, and dairy
  • Insect bites and stings
  • Medications, including ibuprofen and certain antibiotics like penicillin 
  • Latex
  • Household chemicals like those used in detergents and hair dyes

Note that you’ll be more likely to have an allergy if:

  • Your family has a history of asthma or allergies
  • You are a child, and your siblings or parents have allergies or asthma
  • You have asthma or an allergic condition


Allergies are caused by an overreaction of your immune system to allergens. Common allergens include food, grass and tree pollen, dust mites, mold, medications, and insect bites.

Signs and Symptoms of Allergies

Allergic reactions depend on the allergen involved and can affect different parts of your body. Allergy symptoms can be mild to severe. Severe allergies can trigger a dangerous reaction known as anaphylaxis. Common symptoms of allergies include:

Types of Allergies

There are many types of allergies. They can be caused by different allergens and have different types of symptoms.

Hay Fever

Hay fever, also known as allergic rhinitis, is a type of allergy triggered by pollen from trees, weeds, and grasses. Each spring, summer, and fall, trees, weeds, and grasses release tiny pollen grains into the air. Some of the pollen ends up in your nose and throat. Hay fever affects 40 million to 60 million Americans.

Symptoms of allergic rhinitis can include:

  • Sneezing, often with a runny or clogged nose
  • Coughing and postnasal drip
  • Itchy eyes, nose and throat
  • Red, watery eyes
  • Dark circles under the eyes

Atopic Dermatitis

Atopic dermatitis is a type of eczema, and causes your skin to become red and itchy. The American Academy of Dermatology estimates that one in 10 people have this condition.

Atopic dermatitis is due to a reaction in the skin. The reaction leads to ongoing itching, swelling, and redness. People with atopic dermatitis may be more sensitive because their skin lacks specific proteins that maintain the skin's barrier to water.

Atopic dermatitis can be caused by allergies. In some children, food allergies and dust mite allergies play a role in the development of atopic dermatitis.

The following can make atopic dermatitis symptoms worse:

  • Allergies to pollen, mold, dust mites, or animals
  • Cold and dry air in the winter
  • Colds or the flu
  • Contact with irritants and chemicals
  • Contact with rough materials, such as wool
  • Dry skin
  • Emotional stress
  • Drying out of the skin from taking frequent baths or showers and from swimming
  • Getting too hot or too cold, as well as sudden changes in temperature
  • Perfumes or dyes added to skin lotions or soaps

Drug Allergies

A drug allergy occurs when your body’s immune system becomes sensitized to a substance in a medication, perceives it as a foreign invader, and releases chemicals to defend against it. Common triggers of drug allergies:

  • Penicillin and related antibiotics
  • Antibiotics containing sulfonamides (sulfa drugs)
  • Anticonvulsants
  • Aspirin, ibuprofen, and other nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Chemotherapy drugs

An allergic reaction to drugs can affect any part of your body. Common symptoms include:

  • Hives
  • Itchy skin
  • Rash
  • Swelling
  • Wheezing

Anaphylaxis, a potentially life-threatening reaction, can also occur.

Food Allergies

A food allergy is an abnormal response to a food triggered by your body's immune system. In adults, the foods that most often trigger allergic reactions include fish, shellfish, peanuts, and tree nuts, such as walnuts. Problem foods for children can include eggs, milk, peanuts, tree nuts, soy, and wheat.

A food allergy can cause:

  • Itching or swelling in your mouth
  • Vomiting, diarrhea, or abdominal cramps and pain
  • Hives
  • Tightening of the throat and trouble breathing
  • Drop in blood pressure

When you have food allergies, you must be prepared to treat an accidental exposure. Wear a medical alert bracelet or necklace and carry an auto-injector device containing epinephrine.

Insect Sting Allergies

Insect sting allergies occur when your immune system overreacts to the venom in insect stings. Stinging insects include:

  • Yellow jackets
  • Honeybees and bumblebees
  • Paper wasps
  • Hornets
  • Fire ants

Insect sting allergies can cause the following symptoms:

  • Swelling at the sting site
  • Itching 
  • Cough
  • Difficulty breathing
  • Anaphylaxis

Ways to Recognize an Allergy

Even though it may not be easy to tell if you have an allergy, there are a few ways that you can differentiate an allergy from other conditions.

Make a Checklist of Symptoms

It may be difficult for you to differentiate between an allergy and a cold because both come with similar symptoms. It that is the case, it would be best to write down the symptoms you are experiencing. 

If you have a fever, green mucus, and body aches, then you most likely have a cold. However, if you have sneezing, watery eyes, clear mucus, and itchy eyes, ears, nose, or throat, you most likely have an allergy.  

Note What Time Allergy Symptoms Occur

Noting the time span and exact time you have these allergic reactions can help you discover the cause. A cold generally lasts between five to seven days. If allergy symptoms last for more than two weeks or for months at a time, you may have a seasonal allergy.

If your symptoms worsen during the spring or fall, when pollen counts are higher, then you are more likely to have a seasonal allergy. If you have allergic reactions around the clock, you should check to see if there are allergens in your environment like dust mites. 

Rule Out Other Conditions

Some disorders are often misdiagnosed as food allergies. Also, food intolerance is often confused with allergies. Food intolerance is your body's response to what you eat. For example, people who are lactose-intolerant react to milk products. As a result, they experience abdominal pain due to gas. Although the symptoms may be similar to those of a food allergy, they should not be confused.


It’s best to see an allergist or immunologist if your allergic reaction lasts more than two weeks or more and recurs often.

Skin tests are commonly used to identify the allergens that are causing your allergy symptoms. Your allergist will prick your skin with the extract of an allergen and then check for a reaction.

A blood test can also be performed. It checks the amount of antibodies your immune system produces. A higher count shows that you may be allergic to the allergen.You should note, however, that this test is not as sensitive as a skin test.

Management and Prevention

Even though staying away from the allergen seems like the best way to treat an allergy, it isn’t the most efficient in emergencies. Some common treatment methods include the following:

  • Medications: Antihistamines or steroids are commonly used to treat allergies like allergic rhinitis and allergic conjunctivitis (inflammation of the whites of the eyes). These drugs come in tablets, injections, and nasal sprays. Your doctor may also recommend steroid creams. 
  • Allergen-specific immunotherapy (desensitization): Also known as desensitization, this method exposes you to little bits of the allergen at regular intervals. These can be given as drops under the tongue or by injection. It takes three to five years to complete the therapy. This treatment method is used in treating pollen, dust, or insect sting allergies.

Preventing allergic reactions is easier than treating them. General preventive strategies include:

  • Avoiding allergy triggers: Despite whether you are undergoing treatment, it helps if you avoid the allergens that cause your reaction. For example, people allergic to pollen should stay indoors when the pollen count is high. Those allergic to dust or pets should keep their environment clean and stay away from pet dander. Look for a vacuum with a high-efficiency particulate air (HEPA) filter.
  • Wearing a medical alert device/mobile medical alert app: If you've experienced severe allergies, it is important you wear a medical alert device or have a mobile app that will let close friends and families know when you run into that kind of trouble. 
  • Noting the symptoms and triggers: A good way to avoid allergies is by finding out the cause. Write down what you do or eat and if there are any symptoms associated with your actions. This may help you and your allergist discover your allergens.


Avoiding allergy triggers is a common way to manage and prevent allergies, but that is not always enough. Over-the-counter (OTC) medications and immunotherapy can treat allergies. Make a note of your triggers so you and your doctor can determine ways to keep your allergy under control. Also, wear a medical bracelet in case you can't communicate when you experience a severe allergic reaction.

When to See A Doctor

If OTC allergy drugs don’t stop the allergic reaction, see your doctor immediately. Also, if you notice an allergic reaction after starting a new drug, reach the doctor that recommended it immediately. 

In severe cases, like anaphylaxis, seek emergency medical assistance. If you have epinephrine on you, self-administer the medication as soon as you notice symptoms of an allergic reaction.

You should still visit the emergency room after the injection. If you have had an anaphylactic reaction before, schedule an appointment to visit your doctor.  


Allergies are your body’s way of fighting off substances that it sees as harmful even when they are harmless. Your body's immune system reacts when triggers to the allergens invade your body. 

Some common causes of these reactions are pollen, pet dander, dust mites, chemicals, or even insect bites. 

Ways to manage allergies are by taking over-the-counter medications or prescription medications as recommended by your healthcare professional. It is also important to avoid potential triggers that might cause reactions. In serious cases, dial 911 or visit the nearest emergency ward to receive adequate medical attention. 

A Word From Verywell

Allergies are common but not deadly as long as they are kept under control. Educating yourself and taking the right precautions can help you live through these episodes. However, don’t forget to always inform your doctor if you notice symptoms that are not normal in your body.

Frequently Asked Questions

  • How do you know if you have allergies or a cold?

    Allergies and colds share symptoms like sneezing and stuffy or runny nose, headache, and fatigue. However, what they don’t share is a fever. You will not get a fever if you’re having an allergic reaction.

    Also, you don’t experience itchy ears with the common cold the way you would with allergies. Note, too, that it is rare to experience muscle aches or sore throats when having allergies. 

  • How do you know if you have allergies or a sinus infection?

    Both allergies and sinus infections come with a stuffy nose. Nevertheless, they have their differences. A sinus infection arises from an allergy. With sinusitis, you may have thick mucus, postnasal drip, cough, sore throat, and fatigue. Whereas with allergies, you mainly experience a runny nose, sneezing, watery eyes, and wheezing.

  • How long do allergies usually last?

    The time it takes for an allergic reaction to stop depends on the type of reaction (allergic rhinitis, rash, anaphylaxis) and whether exposure to the allergy trigger (allergen) is continuing.

    You are likely to have allergy symptoms with seasonal allergies as long as you are exposed to the allergy trigger (such as pollen), which can be two or more months each year. You may have ongoing exposure when you have allergies to mold, dust mites, or pet dander.

    You may continue to have an allergy for the rest of your life once you develop it. However, some people find that over the years they no longer have symptoms when exposed to an allergen.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  4. Asthma and Allergy Foundation of America. Types of allergies.

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  6. American Academy of Dermatology Association. Eczema types: Atopic dermatitis overview.

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  8. American College of Allergy, Asthma & Immunology. Drug allergy.

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Additional Reading

By Margaret Etudo
Margaret Etudo is a health writing expert with extensive experience in simplifying complex health-based information for the public on topics, like respiratory health, mental health and sexual health.