It can be difficult to tell the difference between pink eye and allergies, as both can lead to red, sore, and inflamed eyes. However, pink eye is a bacterial infection, which often causes thick discharge, too.

The discharge from pink eye, which refers to bacterial conjunctivitis, contains pus. As it dries, this pus may leave crust around the eye.

Eye irritation from allergies, or allergic conjunctivitis, is less likely to cause this symptom. The eyes may feel itchy and have watery discharge instead.

This article explains how to tell the difference between pink eye and allergies, what treatments may help, and how to help prevent the spread.

An illustration showing a healthy eye, an eye with watery discharge, and an eye with pus.Share on Pinterest
Different types of conjunctivitis can cause distinct symptoms. Illustration by Wenzdai Figueroa.

Pink eye and allergies can produce similar symptoms in and around the eyes. This is because they can lead to conjunctivitis, or inflammation of the conjunctiva. The conjunctiva is the thin membrane that protects the eyes and the inside of the eyelids.

Pink eye, or bacterial conjunctivitis, occurs due to an infection. Both viruses and bacteria can potentially cause conjunctivitis, but the term “pink eye” usually refers to bacterial infections.

Bacterial conjunctivitis occurs when bacteria come into contact with the eye, usually due to direct contact with someone else who has the condition.

Viral conjunctivitis occurs when a person has a viral infection, such as a cold or flu, that then leads to eye symptoms. This type is also contagious.

Allergic conjunctivitis is not caused by an infection, so it cannot spread. It occurs as a reaction to allergens coming into contact with the eyes.

Less commonly, other things can lead to conjunctivitis, such as fungi, irritants, or parasites.

All types of conjunctivitis can cause the following symptoms:

  • pink or red eyes
  • watery eyes
  • soreness
  • itchiness
  • blurry or hazy vision
  • sensitivity to light

However, some symptoms are more common in certain types of conjunctivitis than others. The table below summarizes the typical differences:

Viral conjunctivitisBacterial conjunctivitisAllergic conjunctivitis
• recent viral infection, such as a cold
• watery discharge
• swollen lymph nodes
• thick white or yellow discharge
• crusting or matting of the eyes, especially on waking up
• a sensation that something is in the eyes
• less commonly, swollen lymph nodes
• intense itchiness
• puffy eyelids
• watery discharge
• history of allergies
• no swollen lymph nodes

The early symptoms of viral, bacterial, and allergic conjunctivitis are all very similar. The eyes may start to feel irritated, look more red or bloodshot than usual, and water more.

However, allergic conjunctivitis usually occurs in both eyes at once. Bacterial and viral conjunctivitis can begin in one eye before spreading to the other.

To determine what kind of conjunctivitis a person has, a doctor will assess their history and look for distinctive symptoms of each condition.

Viral conjunctivitis occurs alongside a cold or respiratory tract infection. It also causes the eyes to produce thin, watery discharge. In contrast, bacterial conjunctivitis usually produces a thick discharge with a yellow or green color.

A distinctive symptom of allergic conjunctivitis is itchiness. This symptom may be more intense than with other types of conjunctivitis and only occurs when a person is in certain situations or environments. This may indicate they are allergic to something around them, such as pollen or dust.

In most cases, infectious conjunctivitis goes away by itself. Viral conjunctivitis typically gets worse over 4–5 days but then goes away on its own over 1–2 weeks.

Bacterial conjunctivitis can go away without treatment, too, improving over 7–10 days. Doctors may prescribe antibiotics to speed up recovery, limit the chance of complications, and reduce transmission to others. They usually come in the form of eye drops or an ointment.

Antibiotics are especially important in cases where the person has a compromised immune system, or certain types of bacteria are present.

The best way to treat allergic conjunctivitis is to get the person away from the allergen that triggers their reaction. This could mean vacuuming and dusting to eliminate dust mites or staying indoors on days with a high pollen count, for example.

In cases where it is difficult or impossible to get away from an allergen, allergy medications such as antihistamines can help. A person can usually purchase these over the counter, but in more severe cases, a doctor can prescribe stronger medications.

Allergic conjunctivitis does not spread from one person to another, but pink eye does. To avoid the spread of pink eye, a person can try:

  • using a clean towel, tissue, or cotton pad to clean the eyes, and not reusing it
  • avoiding touching or rubbing the eyes, as this can worsen symptoms and spread the bacteria or virus to other areas
  • washing the hands regularly and thoroughly with soap and water, especially after sneezing, coughing, or going to the bathroom
  • not using eye makeup while the infection is ongoing
  • stopping the use of contact lenses until a doctor says it is safe to use them again
  • cleaning, storing, and replacing contact lenses according to a doctor’s instructions
  • not sharing personal items that touch the face, such as bedding, towels, or makeup

Below are some answers to some frequently asked questions about pink eye and allergies.

Is pink eye contagious?

Pink eye is contagious, as it is a result of an infection.

Can you have both pink eye and allergies?

Because pink eye and allergic conjunctivitis have different causes, it is technically possible to have both at the same time.

Can you have allergic conjunctivitis in one eye?

Allergic conjunctivitis generally affects both eyes at the same time, but if an allergen only makes contact with one eye and not the other, then yes, this could happen.

People may wish to speak with a doctor if their symptoms do not improve, get worse, or occur with:

  • severe pain
  • vision changes that do not improve after cleaning the eye
  • significant swelling or inflammation of the skin around the eye
  • fever

Newborn babies with conjunctivitis require medical attention right away.

Pink eye and allergies can both cause similar symptoms due to conjunctivitis. However, they have some distinctive symptoms that can help people tell them apart. Pink eye is more likely to cause thick discharge, whereas allergies are more likely to cause watery discharge and itchiness.

It is important to distinguish between bacterial and allergic conjunctivitis because they have different treatments. Mistaking pink eye for allergies could also mean a person does not take precautions to prevent its spread.

If a person is experiencing conjunctivitis symptoms that persist, get worse, or occur with concerning symptoms, such as vision changes or pain, it is best to speak with a doctor.