Allergy Headache: How Allergies Can Cause Headaches

More than 50 million people in the United States suffer from allergies, with many people experiencing seasonal or perennial allergies.

When exposed to a particular allergen (a usually harmless substance that can provoke an immune response in some people), people with allergies can experience symptoms that range from mildly irritating to debilitating.

Allergy symptoms overlap with many other medical conditions, including upper respiratory infections such as the common cold and sinusitis, so it can be hard to know exactly which symptoms correspond to which conditions.

What Are Some Common Symptoms of Allergies?

Each person experiences allergy symptoms differently, and different allergens are known to cause different symptoms.

For example, people with allergies to food, medication, or insect bites are likely to experience symptoms such as hives, skin irritation, rash, or anaphylaxis.

However, environmental allergens, such as pollen, mold, dust mites, or pet dander, are more likely to cause symptoms that affect the nasal passages.

These symptoms can occur on a seasonal or year-round basis depending on a person’s particular allergens.

Some of the most common symptoms of allergies include:

• Itchy, watery eyes
• Sneezing
• Runny or stuffy nose
• Nasal congestion

Less common symptoms of allergies include, but are not limited to:

• Fatigue
• Sore throat
• Cough

Can Allergies Cause Headaches?

As noted above, there are some situations in which allergies can contribute to headaches.

However, headache is not a common symptom of allergies.

People often confuse allergies with sinusitis because many of the symptoms are the same; both allergies and sinusitis can cause nasal congestion, a runny nose, and itchy, water eyes.

Like allergies, the symptoms of sinusitis can also vary depending on the season, the time of year, and exposure to allergens.

While both allergies and sinusitis can contribute to headaches, sinusitis is more likely to cause headaches than allergies.

When allergies, or allergic rhinitis, are the cause of your headache, it is because the tissues of the nasal passages have become inflamed due to exposure to an allergen.

The tissues that line the nasal cavity and sinuses become inflamed, contributing to excess production of mucus, runny nose, and more.

This inflammation can be painful and can cause a headache to occur; the headache will feel like it is located at the front of the head.

It is more common for sinusitis to contribute to headaches. When an individual experiences sinusitis, the sinuses become swollen and inflamed.

As a result of the infection, the nasal passages become blocked and excess mucus is trapped in the sinuses, causing a buildup of pressure.

The increased pressure in the sinus cavities can cause a sinus headache, which is felt at the top of the head or behind the cheeks and eyes.

It is also common for people with sinusitis to think that their sinus problems are contributing to their headaches when they are actually experiencing migraine headaches instead.

Due to the overlap of symptoms, it can be challenging to determine which medical condition is actually causing your sinus headache.

A study conducted in 2004 found that 88 percent of people who thought they were experiencing a sinus headache were actually suffering from a migraine headache instead.

How Can You Treat Allergy Symptoms?

If you are among the 20 percent of Americans who suffer from symptoms of allergic rhinitis, you know how inconvenient and even debilitating an allergy attack can be. 

As a result, pharmaceutical companies have increasingly focused their research and development efforts on developing new medications that can be used to treat allergy symptoms.

Many allergy medications were previously available by prescription only, but today, there are many over-the-counter medication options as well.

There are three main classes of drugs that are used to treat symptoms of allergies, including allergy headaches: antihistamines, decongestants, and corticosteroids.

Antihistamines

Antihistamines are among the most well known medications used to treat symptoms of allergies.

These medications, which include active ingredients like diphenhydramine, the active ingredient in Benadryl, work by blocking the action of the histamine chemical in the body.

Antihistamines work quickly to treat symptoms of allergies, so they are often used for the treatment of acute symptoms.

There are two major types of antihistamines: first-generation antihistamines and second-generation antihistamines.

First-generation antihistamines include diphenhydramine. First developed in the 1930s, first-generation antihistamines cross the blood-brain barrier and work on the histamine receptors in the brain and spinal cord.

As a result, first-general antihistamines are associated with more side effects than second-generation antihistamines and the side effects may be more severe.

• Drowsiness
• Blurred or double vision
• Mucous thickening in the airways
• Rapid heart rate
• Dizziness and headache
• Low blood pressure
• Dry mouth, dry eyes
• Difficulty urinating and constipation

Second-generation antihistamines include medications like cetirizine, the active ingredient in Zyrtec.

These medications were developed beginning in the 1980s with the intent of reducing the side effects associated with first-generation antihistamines.

Because this category of antihistamines does not cross the blood-brain barrier to the same degree as first-generation antihistamines, they are associated with fewer side effects and the side effects they do cause are less severe.

They also interact with fewer drugs and are better suited to everyday use for the treatment of allergy symptoms.

Some of the common side effects of second generation antihistamines include:

• Headache
• Sore throat
• Abdominal pain or discomfort
• Cough
• Tiredness
• Nausea or vomiting

Decongestants

Decongestant medications also act quickly to treat allergy symptoms. This class of medications includes pseudoephedrine and comes in the form of tablets, nasal sprays, pills, and liquids. 

Decongestants work by narrowing swollen blood vessels that line the nasal passages.

These blood vessels become swollen when the body is exposed to an allergen, causing the tissues that line the nasal passages and sinuses to become inflamed.

The body begins to produce excess mucus, causing the nasal passages, sinuses, and throat to become congested and clogged, which makes it difficult to breathe.

Because congestion is painful and uncomfortable, decongestants focus on relieving congestion and making it easier to breathe.

Decongestants can be particularly helpful in relieving the symptoms associated with congestion and excess mucus, including sinus headache.

Decongestant medications have fewer side effects than antihistamines, and the side effects that do result are typically mild. Side effects that are commonly associated with decongestants include:

• Drowsiness
• Feeling sick
• A rash
• A dry mouth
• Headaches
• Feeling restless or agitated
• Irritation of the lining of your nose

One of the potential effects associated with nasal decongestants is a rebound effect when used for longer than three days at a time.

When used for more than three days, nasal decongestant medications can cause congestion to become worse after initially making it better. 

However, decongestant medications can be used on a short-term basis to improve symptoms.

Corticosteroids

Corticosteroid medications are another popular type of allergy medication. Corticosteroids are most commonly used in the form of nasal sprays to treat allergies, and one of the most common active ingredients is fluticasone.

Corticosteroids work to relieve allergy symptoms by reducing inflammation in the tissues of the nasal passages.

When exposed to an allergen, the tissues of the nasal passages become inflamed, causing the body to produce excess mucus.

Steroid medications reduce inflammation in the body’s tissues, and corticosteroids are delivered directly to the nasal passages via nasal spray. 

As a result, the medication is able to specifically target the tissues of the nasal passages without having similar effects on other tissues in the body. 

Side effects associated with corticosteroids for allergies include:

• Burning, irritation, or drying inside the nose
• Throat irritation
• Itchiness in the throat
• Sneezing

Unlike antihistamines and decongestants, corticosteroids are not well suited for the treatment of acute allergy symptoms.

These medications can take up to two to four weeks before they reach full effect, so they are best used on a consistent basis for the prevention of allergy symptoms.

Summary

Allergic rhinitis can cause a variety of symptoms, including itchy, watery eyes, sneezing, runny nose, and nasal congestion. Less commonly, allergy symptoms may include headache, sore throat, fatigue, and cough.

There are many ways to treat allergy symptoms, but three classes of medications that are most commonly used to relieve symptoms include antihistamines, decongestants, and corticosteroids.

Medications that reduce congestion in the nasal passages and sinuses are the most helpful for reducing symptoms of headache caused by allergies.

References, Studies and Sources:

Prevalence of Migraine in Patients With a History of Self-reported or Physician-Diagnosed “Sinus” Headache | JAMA Internal Medicine 

Corticosteroids | Cleveland Clinic

Allergy Statistics in the US | Allergy and Asthma Network