Drowsiness can be a side effect of inflammation, disrupted sleep and, sometimes, your allergy medicine
Person resting head on their arms, with different types of allergens all around
When you hear the word “seasonal,” you probably think of itchy eyes, a runny nose and uncontrollable sneezing — classic signs that your body is reacting to an allergen.
But what about feeling tired and fuzzy-headed? Why does that happen?
Allergist and immunologist Mark Aronica, MD, explains the relationship between allergies and fatigue.
Why your seasonal allergies cause fatigue
Allergens themselves won’t make you exhausted. But you could be tired from the combination of disrupted sleep, medication side effects and your body working overtime to fight off allergens.
Let’s dig deeper into why you may be more tired than usual and what you can do about it.
Immune response
When you have an allergic reaction to something like dust or pollen, your immune system goes into overdrive to fight what it sees as a threat. The same thing happens when you’re sick.
Exposure to an allergen triggers the release of proteins called cytokines. Along with other chemicals, like histamine, they help coordinate your immune response and trigger inflammation.
“That inflammation leads to nasal congestion, disrupted sleep patterns and not getting good rest,” says Dr. Aronica.
Poor sleep
Histamines and cytokines play a vital role in regulating your body’s sleep-wake cycle. When an allergic reaction throws that delicate balance off, it can make it harder to fall and stay asleep. Symptoms like congestion, eye irritation and a runny nose can also keep you awake.
Poor sleep can make fatigue even worse, too. When you’re not getting enough quality rest, you may wake up feeling exhausted — making it even harder to get through your day as your body continues to deal with allergy symptoms.
If you’re relying on more caffeine to stay awake, that can make it even harder to fall asleep at night, adding to your exhaustion.
Medications
Certain antihistamines — both over-the-counter and prescription — can cause drowsiness.
But second-generation antihistamines are less likely to make you tired, including:
Loratadine
Fexofenadine
Cetirizine
That’s because these medications were designed not to cross the blood-brain barrier as easily as first-generation antihistamines, like diphenhydramine, chlorpheniramine and hydroxyzine, which are known for causing drowsiness.
But even second-generation antihistamines can make you tired for different reasons:
You take other medications. The more medications you’re taking, the greater the chance they’ll interact, causing side effects.
You drink alcohol. It’s never good to mix antihistamines and alcohol. This can cause extreme fatigue, dizziness, confusion, liver damage and more.
Your body reacts differently. Medications affect everyone differently. You might be more sensitive to second-generation antihistamines.
If you think your medication is making you more tired than usual, ask a healthcare provider or pharmacist about switching to another one or consider taking them at night.
The deal with ‘allergy fatigue’
The term “allergy fatigue” is a bit misleading. It’s not the allergens that make you tired, it’s everything else — from inflammation and symptoms to disrupted sleep. Together, these can all bring on “brain fog” — a hazy, tired feeling that makes it difficult to concentrate.
“Chronic inflammation from allergies can lead to that foggy feeling,” explains Dr. Aronica. “The more fatigued you are, the harder it is to focus in school or at work. It can also negatively impact your quality of life if you’re too tired to do things you would normally do, like work out.”
If your allergies act up and you feel the fog rolling in, Dr. Aronica recommends at-home allergy remedies, like staying inside during peak allergen hours or using artificial tears.
If those don’t work, contact your primary care provider or an allergist to get further testing — and fatigue relief.