50 million Americans find themselves dealing with the familiar sniffs and sneezes of allergies every year.
But there’s one symptom many forget: allergy fatigue.
When discussing allergy symptoms, most people are surprised to hear that allergies cause fatigue.
In addition to more well-known allergy symptoms, many people with allergies report a mental sluggishness and exhaustion that’s come to be called “brain fog.”
But how do allergies cause brain fog? To answer this question, it’s important to understand what allergies are and how they work.
What are Allergies?
Put simply, allergic reactions are genetic reactions to non-harmful substances that your body perceives as threats.
When met with a foreign threat – like bacteria or a virus – your body immediately launches an immune response to defuse the threat and restore you to full health.
For many, this system functions optimally, only activating in the case of injury or health threats.
But due to genetic and environmental experiences, some people’s bodies treat non-harmful substances as threats, activating the immune system and leading to frustrating allergy symptoms like fatigue and low energy.
How do Allergic Reactions Work?
When an allergen makes contact, B-cells (a type of white blood cell) immediately register the allergen as a threat and trigger the production of Immunoglobulin E (IgE) from Type 2 Helper T Cells (Th2). Immunoglobulin E then binds with mast cells and basophils that regulate immune responses, triggering the release of inflammatory mediators like histamine.
As the histamine and other chemicals work to heal the injury and ward off the threat, they produce the allergy symptoms most of us know firsthand.
And with environmental allergies like pollen or dust, these symptoms can persist for weeks at a time.
Allergy Symptoms
Although allergy reactions vary depending on the type of allergy, most people with mild allergies experience a similar grouping of reactions.
Mild allergy symptoms typically include:
- Runny or congested nose
- Watery eyes
- Sneezing
- Mild rash
More severe allergic reactions are labeled as anaphylaxis and are considered life-threatening.
If someone is prone to anaphylaxis, it’s critical to have an epinephrine pen on hand as symptoms typically occur within the first 20 minutes and can last for 2 hours.
Symptoms of anaphylaxis include:
- Skin rash
- Difficulty breathing
- Nausea
- Vomiting
- Shock
It’s important to remember that symptoms vary by individual and type of allergy.
For example, seasonal allergies present differently than latex allergies, which look different than food allergies, drug allergies, animal allergies, contact dermatitis, and so on.
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So How Do Allergies Make You Tired?
When battling with allergies, many chalk up their fatigue and low energy to stress and other factors. But the truth is, allergies contribute to fatigue in more ways than one.
1. Your Long-Term Immune Response is Exhausting You.
When your body’s in healing mode, it prioritizes its resources to bring you back to health.
With short-term illnesses like colds or the flu, we’ll typically feel tired for a few days and begin regaining energy as we start feeling better.
But with allergies, our immune system stays active for longer than it’s meant to, requiring more resources and energy to keep up the “disease-fighting” histamine and immunoglobulin E activity.
As time stretches on, the inflammation meant to heal us can become chronic and lead to long-term fatigue resulting from diversion and depletion of your body’s energy.
2. You’re Breathing in Less Oxygen.
Stuffed noses and congestion make it harder to breathe and reduce your oxygen intake. With less oxygen comes less energy for our cells to refuel our bodies, making the impact of a long-term immune response even more exhausting on our systems.
3. You’re Not Sleeping Well.
Nasal congestion can make it uncomfortable, if not impossible to get a good night’s sleep. In addition to our decreased oxygen intake, finding a comfortable position to fall asleep can feel like an infuriating pipedream.
Sleep is a restorative process that keeps us healthy – our health declines when we’re deprived of sleep, leaving us more and more fatigued.
4. Your Allergy Medications Are Making You Drowsy.
Certain allergy medications may contribute to your fatigue.
For example, people seeking allergy relief have found older antihistamines like Benadryl often make them feel drowsy.
Antihistamines block histamine receptors in the brain, preventing our brains from triggering the immune response that results in allergy symptoms.
However, antihistamines also block the histamine receptors that help us stay alert, making us feel sleepy.
Second-generation antihistamines like Zyrtec tend to have less fatigue-inducing properties and may be a better choice if you’re feeling drowsy.
How to Treat Allergy Fatigue
The brain fog and exhaustion of allergy fatigue can be frustrating, but they are not without solutions!
Before anything else, it’s advisable to talk to a physician or allergist to determine exactly what you’re allergic to.
They’ll likely perform an allergy test – usually a blood or skin test – to figure out exactly what triggers an allergic reaction in your system, so you can do your best to avoid that allergen.
Aside from avoiding your allergy, there are a number of other ways you can reduce allergy symptoms, and with them – allergy fatigue.
1. Allergy Medication.
Several medications provide relief for allergy symptoms.
Decongestants and nasal sprays can make it easier to breathe, and antihistamines help reduce allergy symptoms.
It’s important to remember that some antihistamines may make you drowsy, but that can actually be a plus if you’re having trouble falling asleep! If you’re trying to stay awake, non-drowsy allergy relief like Claritin or Zyrtec may be better options.
2. Try a Saline Wash.
Many people find that nasal irrigation using nasal flo or a neti pot helps clear sinuses and relieve congestion and headaches.
If you’re using a neti pot, be sure to clean it thoroughly between uses.
3. Ask your Doctor for an Allergy Shot.
Also known as immunotherapy, allergy shots help your body develop resistance to current allergens.
Each shot delivers a slightly larger dose of allergens than the last, helping your body build up immunity and lessen the severity of its allergic reaction.
4. Clean Up Around the House.
Some of the most common allergens include dust and pollen. You can help reduce exposure to allergens by dusting, vacuuming, and washing the sheets regularly.
Additionally, keeping pets off furniture, making sure the bathroom is well ventilated, using air conditioning instead of opening windows, and monitoring for high pollen days can help you reduce allergen exposure and symptoms.
References, Studies and Sources:
ncbi.nlm.nih.gov/pmc/articles/PMC1661616/
academic.oup.com/sleep/article/35/6/727/2709360

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Chris is one of the Co-Founders of Pharmacists.org. An entrepreneur at heart, Chris has been building and writing in consumer health for over 10 years. In addition to Pharmacists.org, Chris and his Acme Health LLC Brand Team own and operate Diabetic.org and the USA Rx Pharmacy Discount Card powered by Pharmacists.org.
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