Sneezy and dopey? Seasonal allergies and your brain – Harvard Health

Ah, ’tis the season for warm-weather allergies caused by trees, grass, and ragweed pollen. You know the signs: sneezing, watery eyes, stuffiness, scratchy throat, wheezing, and coughing. But what about so-called brain fog? That may be true for you, too.

Why do allergies make your brain feel so foggy?

“Allergy symptoms can disrupt sleep and make people feel more tired and groggy,” says Dr. Mariana Castells, an allergist and immunologist in the division of Allergy and Clinical Immunology at Harvard-affiliated Brigham and Women’s Hospital. “Plus, your body can become weaker as it fights the inflammation triggered by allergies, contributing to overall fatigue and making it harder to concentrate and focus.”

What happens to your immune system when you inhale pollen?

When you inhale pollen, your immune system generates antibodies called immunoglobulin E (IgE). Those antibodies trigger the release of chemicals called mediators, such as histamine, leukotrienes, and prostaglandins. The chemicals affect tissues in the eyes, nose, and throat,  causing symptoms like sneezing and watering eyes.

4 ways to prevent or ease brain fog stemming from seasonal allergies

Managing your allergy symptoms when they first appear — or taking preventive measures if you are prone to pollen allergies — is the best way to control the allergic immune response that can cause fatigue and brain fog. These four strategies can help.

Lower your exposure to pollen

• Keep your windows closed whenever possible, and occasionally run an air conditioner or use an air purifier with a HEPA filter to help remove pollen from indoor air.
• Pollen is usually highest from about 4 a.m. to noon, so restrict outside time to the late afternoon or evening.
• You can check daily pollen counts in your area and sign up for high pollen alerts at www.pollen.com.
• Wearing a mask outside when pollen is high can block about 70% to 80% of pollen, says Dr. Castells.

Be prepared with over-the-counter allergy medicines

Over-the-counter (OTC) allergy medicines treat many symptoms, thus helping to lift brain fog. It’s best to talk to your doctor or pharmacist before starting any new medicine, especially if you have any health problems or take other medicines.

Options include:

• Non-drowsy antihistamine pills and nasal sprays. Antihistamines block the effects of excess histamine that causes itchy and watery eyes, sneezing, and a runny nose. Sprays also help with congestion and postnasal drip. “Be aware that even non-drowsy brands have potential for some sedation that can affect thinking,” says Dr. Castells. “People tolerate antihistamines differently, so you may have to try more than one brand to assess effectiveness and potential side effects.” Loratadine (Claritin), cetirizine (Zyrtec), and fexofenadine (Allegra) are less sedating than first-generation antihistamines such as diphenhydramine (Benadryl).
• Decongestant pills, such as phenylephrine (Sudafed PE) and pseudoephedrine (Sifedrine, Sudafed). Decongestants shrink tiny blood vessels, which decreases fluid secretion in nasal passages, helping to unclog a stuffy nose. However, they can increase heart rate and blood pressure. They are not recommended for prolonged use, so check with your doctor if you have heart or blood pressure problems. Decongestant nasal sprays, such as oxymetazoline (Afrin), may be used for several days, but continued use can lead to worsening nasal congestion.
• Combined antihistamine and decongestant medicines have “D” added at end of brand names, such as Zyrtec-D, Allegra-D, and Claritin-D, which combine different antihistamine medicines with the decongestant pseudoephedrine.
• Nasal steroid sprays, such as triamcinolone (Nasacort), budesonide (Rhinocort), and fluticasone (Flonase), reduce inflammation that causes congestion, runny or itchy nose, and sneezing. “It’s often best to take them before pollen season begins, especially if you are susceptible to allergies,” says Dr. Castells. Side effects may include nasal dryness and, rarely, nose bleeds. People with glaucoma should take these cautiously, as they can raise the pressure inside the eye, leading to potential vision loss.

Consider prescription allergy shots or tablets

If allergies are severe or OTC remedies aren’t sufficient, an allergist may recommend allergy shots, or possibly tablets designed to treat certain allergies.

• Allergy shots are regular injections of small amounts of your allergen, with the dose gradually increasing over time. “Allergy shots do not completely eliminate your allergy but change your immune response to better tolerate it,” says Dr. Castells. During a buildup phase, the allergen dose increases gradually in once or twice weekly shots for three to six months. During the maintenance phase, you get monthly injections for three to five years. “When you’re finished, the protective effect can last several years,” says Dr. Castells.
• Tablets to treat grass and weed allergies offer similar protection as injections. These tablets are dissolved under the tongue. Dr. Castells says they should be used daily before and during the pollen seasons for at least five seasons.

Try a nasal rinse

Prefer to skip medications? Try clearing your nasal cavity twice daily using saline solution in a small bulb syringe or neti pot, which resembles a small teapot with a long spout. Both are sold at drugstores and online. Performed once in the morning and in the evening, this simple technique rinses away pollen.