Do allergies make you tired?

Allergies are immune system responses to substances in our environment that are usually harmless. One of the most well-known allergies is hay fever, a reaction to pollen from trees and grasses. In Germany, approximately 25–37% of the population is currently affected by allergies (RKI, 2023). The trend is increasing, and it is expected that by 2050, half of all Europeans will suffer from allergies (EAACI, 2024). This development has multiple causes, including climate changes such as increased air pollution, rising temperatures, and longer pollen seasons. Common allergy symptoms include a runny nose, sneezing, itching, and breathing difficulties. But can allergies also cause fatigue? The answer is yes. Allergies can lead to fatigue in several ways, for example by disrupting healthy sleep. In this article, we explain how allergies can cause tiredness, whether all allergies have this effect, and offer tips on diagnosis and relief of symptoms.

Table of Contents

• What exactly are allergies?
• Why can allergies cause fatigue?
• Why can allergies cause fatigue?
• How can I prevent allergy-related fatigue?
• Summary

What exactly are allergies?

Allergies occur when the immune system overreacts to normally harmless substances, known as allergens, mistakenly identifying them as harmful. An allergy develops in two steps: first, the body becomes sensitized through repeated exposure to the allergen, such as specific proteins in grass pollen. During this sensitization phase, the body produces specific antibodies—immunoglobulin E (IgE)—against these foreign substances. Upon renewed contact with the allergen, these antibodies are activated and trigger an immune defense response, which leads to the typical allergy symptoms. Normally, this antibody response is a protective mechanism of the body, but in the case of allergies, the immune system mistakenly reacts to harmless substances. The symptoms can vary depending on the type and severity of the allergy (Cleveland Clinic, 2022).

What types of allergies are there?

Many people suffer from allergies, and the triggers can vary greatly. Being informed about different allergens can help you better identify and avoid your own triggers. Allergies are typically classified as follows:

Source: Mayo Clinic, 2022

Why can allergies cause fatigue?

Allergies are not only known for causing typical symptoms like sneezing, itching, and breathing difficulties—they can also lead to fatigue. Here’s why:

1 – Allergies trigger the release of fatigue-inducing substances
Every time the body comes into contact with an allergy-causing allergen, it launches a defensive response. This immune reaction involves the release of histamine and other chemical substances that cause inflammation in the body and lead to common allergy symptoms. This process consumes a great deal of energy and can result in general fatigue. The constant activity of the immune system also puts the body in a state of continuous alert, adding further strain. It is therefore important to identify potential allergens and avoid them as much as possible to reduce the burden on the body (Goretzki et al., 2022).

2 – Allergy medications can cause fatigue
Medications used to treat allergies can also lead to tiredness and drowsiness. Antihistamines are the first-line treatment for allergic reactions. They block the effects of histamine, which is released during an allergic reaction and contributes to typical symptoms. There are two generations of antihistamines:

• Older antihistamines, also known as first-generation antihistamines, can cause side effects such as drowsiness and fatigue. These include clemastine, dimetindene, and doxylamine.
• Newer antihistamines, or second-generation antihistamines, are less likely to cause drowsiness, although it can still occur. Examples include azelastine, bilastine, and cetirizine.

The effects of antihistamines can vary greatly between individuals. Antihistamines are available in various forms, including tablets, capsules, liquids, creams, eye drops, and nasal sprays. If you experience significant fatigue due to your current medication, you should speak with your doctor about alternative treatment options (NHS, 2023; Mayo Clinic, 2024).

3 – Allergies disrupt restful sleep
People with allergies are more than twice as likely to suffer from insomnia compared to those without allergies. Insomnia is the medical term for sleep difficulties—such as trouble falling or staying asleep, insufficient sleep, and poor sleep quality overall. Without restorative sleep, people feel tired and exhausted during the day. Pollen, house dust mite, pet dander, and mold allergies are particularly associated with sleep problems, as these allergens often accumulate in bedrooms—in pillows, duvets, and mattresses. As a result, they intensify symptoms like nasal congestion, sneezing, and itching during the night. Poor sleep quality caused by allergies is a major reason for fatigue, and reducing allergens in the bedroom is essential for maintaining good sleep hygiene (Pacheco & Truong, 2023; Pacheco & Wright, 2023).

4 – Allergies increase the risk of sinus infections
Allergies—especially hay fever—can increase the risk of developing a sinus infection (sinusitis). This occurs when the tissue lining the sinuses becomes inflamed. Allergies cause the sinuses and nasal passages to swell, preventing mucus and fluids from draining properly. As a result, bacteria are more likely to build up, increasing the likelihood of sinusitis. A sinus infection can lead to facial pressure and pain, a blocked nose, and other symptoms such as headaches and fatigue. To reduce the risk of sinus infections, allergy symptoms should be treated promptly and contact with known allergens should be avoided as much as possible (Cleveland Clinic, 2023).

Do all allergies cause fatigue?

Essentially, yes. All allergies can lead to fatigue because the body is heavily engaged in reacting to allergens. This immune activity consumes a lot of energy, which can result in tiredness. Although individual reactions may vary, allergies can be especially exhausting when the body is constantly exposed to the allergen or when the allergy causes significant sleep disturbances (PennMedicine, 2024).

If you suffer from persistent fatigue and exhaustion—whether or not you have visible allergy symptoms—you should consult a doctor to determine the exact cause.

How can I find out if an allergy is causing my fatigue?

Allergy tests can help determine whether you react to specific allergens. The most common allergy tests include:

• Specific IgE blood tests: These tests measure the amount of immunoglobulin E (IgE) antibodies in the blood that respond to specific allergens. This allows for the assessment of the immune system’s sensitivity to certain allergens. An IgE blood test can be done at a general practitioner’s office or at home using a self-test such as the one offered by Homed-IQ.
• Skin prick test: During this test, small amounts of allergens are applied to the skin to observe the body’s reaction. A visible skin response, such as redness and swelling, may indicate that your immune system is reacting to the allergen. This test is carried out by a specialist.

For both tests, the results must be interpreted together with the symptoms experienced in order to make a definitive diagnosis (NHS, 2022).

Want to get an overview yourself?

Homed-IQ offers the opportunity to check your sensitivity level to a wide range of allergens. The Comprehensive Allergy Test measures 295 different allergens linked to 167 specific allergies, while the Inhalation Allergy Test focuses specifically on allergens that are inhaled through the air. Both tests are specific IgE blood tests that can be performed discreetly and conveniently from home. The test results, together with your physical symptoms, can provide valuable insights into potential allergies. It is important to discuss these results with a doctor to receive a clear diagnosis.

How can I prevent allergy-related fatigue?

To avoid allergy-related fatigue, it is important to take certain steps that help relieve symptoms and improve sleep quality. Here are some tips that may help:

1. Identify allergens
If you suspect an allergy, a prick test or an antibody blood test (IgE), such as the one offered by Homed-IQ, can be used. These tests help assess your sensitivity to specific allergens. It can also be helpful to keep a symptom diary. Note when, where, and under what circumstances your symptoms occur. For example, you might notice that your symptoms improve whenever your bedding is freshly washed. By tracking your symptoms closely, you not only feel more in control but also find it easier to avoid the allergen (Mayo Clinic, 2024).

2. Avoid allergens
Once you have identified an allergen, take steps to minimize contact with it. The specific measures will, of course, depend on the allergen and whether it is an indoor or outdoor allergen. For example, if you are allergic to dust mites, you should wash your bedding regularly at 60°C. If you have a pollen allergy, it is advisable to keep the windows closed in the bedroom—especially during pollen season. For more targeted strategies for specific allergies and further information, visit the allergy blog category on our website.

3. Establish good sleep hygiene
To feel less tired, it is especially helpful to adopt habits that improve sleep quality. With all measures, keep this in mind: the lower the exposure to the allergen, the fewer symptoms—and the less strain on the body.

3.1. Can I use antihistamines to sleep better?
It may sound tempting to use antihistamines not only to relieve allergy symptoms but also to sleep better. However, regular use for sleep is not recommended. With frequent intake, tolerance can develop quickly, meaning the sedative effect decreases over time. In addition, antihistamines—especially first-generation ones—can cause side effects such as ringing in the ears, nausea, and stomach pain. If you are unsure or have questions, talk to your doctor about the exact dosage and under what circumstances you can take the medication in the evening (Mayo Clinic, 2023; Mayo Clinic, 2024).

4. Seek medical support
Talk to your doctor, especially if you experience significant fatigue when taking allergy medications, so you can explore alternatives. If your allergy symptoms are severe and noticeably affect your quality of life, it may be advisable to seek professional medical assistance.

An effective treatment option is immunotherapy, also known as desensitization. The goal of this therapy is to gradually accustom the body to the allergen and thereby reduce symptoms in the long term. During this process, small amounts of the allergen are administered to the patient regularly—either through injections (allergy shots) or in other forms such as tablets or drops. Immunotherapy can last several years and is carried out under medical supervision (YaleHealth, 2024).

Summary

Allergies are hypersensitivity reactions of the immune system to substances that are normally harmless, known as allergens. These reactions can lead to fatigue because the body uses energy to fight the allergens, and allergy-related symptoms like nasal congestion and itching can disrupt sleep. In addition, certain allergy medications, such as antihistamines, may cause drowsiness as a side effect. Good sleep hygiene and avoiding allergens can help relieve symptoms and lead to increased energy.