Allergic Conjunctivitis: How Allergies Can Cause Swollen Eyes

Allergies can wreak havoc on your entire body—everything from rashes and sneezing to chest tightness and vomiting. Your eyes can also be affected by allergies by way of a condition called allergic conjunctivitis, or swollen eyes or eyelids, caused by an allergen.

Below, you'll find out about the causes of and treatment options for allergic conjunctivitis, plus when you need to see a healthcare provider for help with your symptoms.

What Causes Allergic Conjunctivitis?

Different allergens can cause allergic conjunctivitis, including animal dander, mold, and dust mites, per MedlinePlus. When your eyes are exposed to an allergy-causing substance, it causes your body to release a substance called histamine. When this happens, the blood vessels in your conjunctivae—the membranes that cover the fronts of your eyes and line the inside of your eyelids—become swollen.

When you're experiencing allergic conjunctivitis, it might be difficult to tell which exact part of the eye is swollen—and the answer isn't always the same, Feryal Hajee, MD, an allergist and immunologist at Metropolitan Asthma and Allergy in Little Silver, NJ, told Health.

Sometimes, when a person is suffering from allergic conjunctivitis, the actual eyeball is swollen. This should warrant an immediate trip to a medical facility. However, at other times, the eyelid is swollen, which should be treated but doesn't necessarily warrant a trip to the emergency room, Dr. Hajee said.

Allergic conjunctivitis has been associated with other allergy-related health conditions, Dr. Hajee said, including eczema (a rash caused by allergies), asthma, and allergic rhinitis (or seasonal allergies). Dr. Hajee added that allergic conjunctivitis can be worse for patients who also suffer from dry eye syndrome.

What Are the Symptoms of Allergic Conjunctivitis?

In addition to the swelling, the following are symptoms of allergic conjunctivitis, according to the American Academy of Allergy, Asthma & Immunology (AAAAI):

• Redness
• Burning
• Itching
• Watery eyes
• Gritty feeling in your eyes

You might also notice symptoms such as an itchy or runny nose and sneezing if you experience allergic conjunctivitis.

How Is Allergic Conjunctivitis Treated?

Oftentimes with allergy symptoms, the best course of action is to simply avoid whatever triggers an allergic reaction. For instance, if you're allergic to cats and you know your friend has a cat, suggest a meeting place outside their home so you don't risk having an allergic reaction to their pet. The same goes for allergic conjunctivitis, Kanwaljit Brar, MD, an allergist at NYU Langone, told Health. "The best approach is to be preventative," Dr. Brar explained.

Experts advised making an appointment with an allergist if you find that you frequently suffer from allergic conjunctivitis with your eyelids swelling and your eyes watering at seemingly random times, as well as if you have no clue what your allergen is. "If you see an allergist, you can identify what you're allergic to; we can predict when patients' symptoms will [happen]," Dr. Brar explained.

From there, an allergist can help you make simple lifestyle changes that eliminate allergic conjunctivitis and other allergy-related issues, Dr. Hajee said. So if your allergist tests you and determines that pollen is likely what's triggering your symptoms, they can advise you to stay inside during certain times of the day when the pollen count in your region is highest, Dr. Brar said. Through tweaking your routine by going on your outdoor run at a different time when the pollen count is typically lower, for example, your symptoms might lessen without the use of medication.

If stronger action is needed, there are plenty of other options available. Your healthcare provider might first recommend taking an antihistamine, though that might not help with allergic conjunctivitis as much as you'd like. "Eye symptoms are notoriously more difficult to treat," Dr. Brar said. Because of that, they may suggest you try eye drops, Dr. Brar added, adding that you can often find ones without a prescription.

If your symptoms are severe, your healthcare provider might recommend allergy shots, which work by slowly building up your body's tolerance to your allergens, according to the AAAAI.

When To See a Healthcare Provider

While your symptoms might clear up once you remove whatever's causing them, you shouldn't hesitate to seek medical help if certain concerning symptoms arise, experts warned.

If your eyeball, rather than your eyelid, is swollen, you should head to a doctor's office immediately, Dr. Hajee said. Additionally, if your eyeball is in any pain, or if any area around the eye is in severe pain, that should prompt a visit to the doctor's office too.

MedlinePlus adds that other symptoms—like if your vision is affected or you have a severe headache—also warrant emergency medical treatment.

A Quick Review

Allergic conjunctivitis is when your eyes or eyelids swell in response to an allergen. If your eye itself is swollen, seek medical care immediately. If your eyelids swell, this is something you can treat by avoiding the allergy trigger (i.e. if you are allergic to dogs, avoid dogs), or via allergy shots, eye drops, or OTC medications. If you have any questions or concerns about allergic conjunctivitis, reach out to a healthcare provider.