Allergic reactions release chemicals that can cause an inflammatory response. This can make a person feel tired.

While allergic reactions can cause tiredness at a chemical level, symptoms of allergies can have the same effect. For example, sinus congestion that results from an allergy can disrupt or prevent sleep.

Also, some allergy medications can lead to drowsiness and have other effects on sleep.

This article looks at what happens in the body during an allergic reaction to cause tiredness and other allergy symptoms. It also describes how to treat allergy-based fatigue.

a man holding his nose because he has an allergy and he is wondering if this can make him tiredShare on Pinterest
A person may feel tired from the inflammatory response of allergies.

When a person comes into contact with an allergen, antibodies in their immune system activate, releasing chemicals to protect the body from the allergen.

The activated antibodies are a type called immunoglobulin E, and they are located on mast cells throughout the body.

Mast cells are present in areas of the body that can come into contact with allergens — areas such as the skin, gut, and airways.

These cells store a chemical called histamine, and they release histamine in response to contact with an allergen, leading to an allergic reaction.

The release of histamine and immunoglobulin E antibodies, as well as an inflammatory response, can cause itching, swelling, narrowing of the airways, and tiredness.

Also, allergic reactions can cause symptoms such as congestion, coughing, and sneezing. These can make sleep difficult, contributing to tiredness.

A third possible cause of tiredness involves allergy medication.

Decongestants, such as pseudoephedrine, and antihistamines can either cause drowsiness or delay sleep, which can cause a person to feel tired the next day.

The right treatment for an allergy can help resolve tiredness and other symptoms. Below, learn more about how to treat an allergy successfully.

Identify allergens

An allergist is a physician with specific training in identifying allergens and treating allergic diseases, such as asthma.

This type of doctor can test the skin or blood to find out which substances trigger an allergic reaction.

Limit or avoid exposure to allergens

Once a person is aware of their allergens, they can take steps to limit or completely avoid exposure.

Some common allergens in the environment include:

  • dust mites
  • pollen
  • animal dander, or flakes of dead skin
  • mold

Taking the following steps can help reduce exposure to these allergens:

  • Clean and dust all living and working spaces regularly.
  • Add dust mite covers to mattresses, box covers, and pillows.
  • Wash bedding every week.
  • Keep bathrooms well-ventilated to avoid dampness.
  • In bedrooms with en-suite bathrooms, open the windows regularly, except during periods of high pollen.
  • Vacuum regularly, especially if there are pets.
  • Avoid letting pets on furniture, especially beds.
  • Brush and bathe pets weekly to reduce dander.
  • Monitor pollen counts.
  • Use air conditioning and keep the windows closed during periods of high pollen.

Take allergy medication

People may find that allergy shots or sublingual tablets provide long-term allergy relief.

These shots or tablets contain very small amounts of the allergen, which helps the body gradually become desensitized to it.

Other allergy medications that may help a person avoid fatigue include:

  • antihistamines
  • decongestants
  • nasal sprays
  • asthma medication, if appropriate

However, because some decongestants and older antihistamines can cause drowsiness, it is crucial to read labels carefully.

A doctor or pharmacist can describe any potential side effects of these drugs and help a person choose the best option.

Fatigue is one of many allergy symptoms. The symptoms of an allergic reaction depend on a range of factors, including the allergen.

Some other typical allergy symptoms include:

  • itchiness in the eyes, nose, and throat
  • sneezing and sniffing
  • coughing
  • hives, which form a raised rash
  • snoring
  • heavy breathing through the mouth
  • wheezing and shortness of breath
  • headaches
  • ear pain or recurring ear infections
  • nosebleeds
  • stomach cramps
  • bloating
  • diarrhea
  • nausea
  • vomiting

Fatigue can cause a person to experience:

  • difficulty concentrating
  • difficulty making decisions
  • irritability
  • an increased risk of accidents or injury
  • reduced hand-eye coordination
  • poor memory
  • reduced performance at work or school

Anyone who experiences allergy symptoms that are concerning should receive medical attention.

Allergies — especially allergies to foods or medications — can be dangerous. For instance, they can cause anaphylaxis, a life threatening reaction that requires emergency medical aid.

Symptoms of anaphylaxis typically appear 5–30 minutes after exposure to the allergen.

Anaphylaxis symptoms may include:

  • wheezing
  • difficulty swallowing
  • hives
  • stomach cramps
  • vomiting
  • a swollen throat
  • fainting

If a person is treating their allergies and still experiences fatigue, but no other allergy symptoms, another underlying health issue may be involved. In this case, a person should see a doctor.

Allergies can make people feel tired for a few reasons.

When the body comes into contact with an allergen, the immune system defends the body by releasing chemicals and antibodies, and the effects can lead to tiredness.

Also, allergy symptoms such as congestion, coughing, and sneezing, can affect sleep and cause tiredness. Some allergy medications, meanwhile, can cause drowsiness or interfere with sleep.

If a person is unsure whether an allergy is at the root of their fatigue, it may be a good idea to see an allergist. If the person has an allergy, they can take steps to reduce their exposure to triggers.

It is important to track allergy symptoms during treatment. If fatigue persists but other symptoms resolve, another underlying health issue may be involved.

If fatigue is interfering with daily life, especially if it is extreme, a person should see a doctor.