TL;DR
Eye allergies and dry eye look almost identical but need different treatments. The biggest giveaway is itching: if your eyes are intensely itchy, it’s almost certainly allergies. If it’s more of a burning, gritty feeling that gets worse through the day, dry eye is more likely.
Allergies tend to come with sneezing and puffy eyelids, while dry eye causes light sensitivity and blurred vision that clears when you blink. You can also have both at once, and allergy medications can actually make dry eye worse.
What causes eye allergies?
Eye allergies, also called allergic conjunctivitis, happen when your immune system overreacts to something harmless in the environment. Pollen, dust mites, pet dander and mould spores are the most common triggers.
When these allergens land on the surface of your eye, your body releases histamine and some other chemicals to fight them off, and that’s what causes the redness, swelling and itching.
There are two main types of eye allergies:
- Seasonal allergic conjunctivitis tends to flare up in spring and summer when pollen counts are high.
- Perennial allergic conjunctivitis sticks around all year and is usually triggered by indoor allergens like dust or animal fur.
If you’ve noticed your eyes reacting to seasonal changes, allergies are a likely culprit, especially if your symptoms come and go with the weather or your surroundings.
What causes dry eye?
Dry eye, or dry eye syndrome, happens when your eyes don’t produce enough tears, or when the tears you do produce evaporate too quickly. Your tear film is made up of three layers: oil, water and mucus. If any one of those layers is out of balance, the surface of your eye dries out and becomes irritated.
Common causes include:
- Ageing (tear production naturally drops after 50)
- Prolonged screen time
- Prolonged exposure to air conditioning
- Central heating
- Certain medications like antihistamines and antidepressants.
- Hormonal changes during menopause can also play a role.
Unlike allergies, dry eye is usually a chronic condition. It doesn’t come and go with the seasons, and it often gets worse over the course of the day, particularly after long stretches of reading or screen use.
The one symptom that sets them apart
Here’s the biggest clue: itching. If your eyes are properly itchy, with that relentless urge to rub them, you’re almost certainly dealing with an allergy. Histamine, the chemical your body releases during an allergic reaction, directly stimulates the itch receptors in your conjunctiva. It’s the defining symptom of allergic conjunctivitis.
Dry eye, on the other hand, tends to produce a burning, gritty or stinging sensation, as if there’s something in your eye. You might also notice your eyes feeling heavy or tired, especially later in the day. But the intense itch that comes with allergies? That’s usually absent with dry eye syndrome.
Other symptoms to compare
Beyond itching, there are a few more differences worth noting.
Eye allergies often cause puffy, swollen eyelids and a watery, clear discharge. You’ll likely have other allergy symptoms too, such as sneezing, a runny nose or a scratchy throat. Both eyes are usually affected at the same time, and symptoms tend to flare up after exposure to a specific trigger.
Dry eye typically causes a scratchy, sandy feeling, sensitivity to light and blurred vision that clears when you blink. Watering can happen with dry eye too (your eyes overcompensate for the dryness), but there’s no swelling or puffiness in the eyelids. Symptoms tend to be worse in dry, windy or air-conditioned environments and after extended periods of concentration.
If you’ve noticed your vision going blurry alongside the dryness, that’s another sign dry eye could be the issue.
Can you have eye allergies and dry eye at the same time?
Yes, dry eye and eye allergies can appear at the same time, and it’s more common than you might think. Allergies can actually make dry eye worse, because the inflammation destabilises your tear film. On top of that, antihistamine tablets, which many people take for hay fever, can reduce tear production and worsen dryness.
This overlap is one of the reasons people struggle to pin down what’s going on. If you have symptoms of both, it’s worth seeing an optometrist who can assess your tear quality and check for signs of allergic inflammation.
How to treat eye allergies
The first step is reducing your exposure to whatever’s triggering the reaction. During high pollen seasons, keep windows closed, shower after being outdoors and avoid drying laundry outside. Wraparound sunglasses can also help keep pollen away from your eyes.
For symptom relief, antihistamine eye drops are usually the most effective option. Cold compresses on closed eyelids will bring down swelling and soothe the itch. Try to avoid rubbing your eyes, even though it feels like it will help. Rubbing releases more histamine and makes the itching worse.
How to treat dry eye
Managing dry eye starts with addressing the root cause. If screen time is a factor, follow the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds. Blinking more consciously while using a computer will also help.
Artificial tears (preservative-free versions are best for regular use) will lubricate the surface of your eye and provide temporary relief. For more persistent dryness, your optometrist may recommend anti-inflammatory drops or suggest using a humidifier at home.
Diet plays a part too. Omega-3 fatty acids, found in oily fish like salmon and mackerel, support the oily layer of your tear film and can reduce evaporation. If you’re interested in how nutrition links to dry eye, it’s worth looking into whether your diet might be falling short.
When to see an optometrist
Most mild cases can be managed at home. But you should book an appointment if your symptoms are persistent, getting worse or affecting your daily life. It’s also worth going if over-the-counter drops aren’t making a difference, or if you’re experiencing pain, significant vision changes or a coloured discharge.
An optometrist can measure your tear production, check for corneal damage and determine whether allergies, dry eye or both are behind your symptoms. Getting the right diagnosis early means you start the right treatment sooner.
Related read: Best Vitamins For Red Eyes
