Flu vaccines are considered very safe, and their safety is monitored by different groups around the world. But in rare cases, you can have an allergic reaction to the flu vaccine or one of its ingredients.

Hundreds of millions of people get a flu vaccine every year, as recommended by organizations like the Centers for Disease Control and Prevention (CDC). Flu vaccines also have to meet very high safety standards because they’re given to healthy people.

But very rarely, some people may have an allergic reaction to a flu vaccine, which may include developing red or swollen eyes. This may make you think you have pink eye, but it’s actually often a sign of a medical emergency when you get red or swollen eyes soon after a flu shot.

There’s also a very rare adverse event associated with flu vaccines called oculo-respiratory syndrome (ORS). One symptom of ORS is conjunctivitis, also known as pink eye.

But can the flu vaccine itself give you pink eye? Read on to learn more.

Medical emergency

Allergic reactions to the flu shot are rare, but they are a medical emergency. Seek treatment right away if you develop any of the following symptoms within a few minutes to a few hours after getting a flu shot:

Allergic reactions to the flu vaccine happen to people who are allergic to one or more ingredients in the vaccine, including gelatin. People who are allergic to certain antibiotics may also have a reaction to the flu vaccine.

If you’re allergic to eggs, it can cause an allergic reaction to the flu vaccine. Many common types of flu vaccines are egg-based, but there are egg-free vaccines.

Talk with a doctor before getting a flu shot if you’re allergic to eggs.

Oculo-respiratory syndrome (ORS) is a type of reaction that can happen after a flu shot. Although it shares some symptoms with an allergic reaction, they’re not the same thing.

Symptoms of ORS usually start between 2 and 24 hours after vaccination and resolve within a few days. Common symptoms include:

  • wheezing
  • chest tightness
  • trouble breathing
  • trouble swallowing
  • red eyes (both eyes)
  • sore throat
  • facial swelling

Most cases of ORS happened in Canada during the 2000 to 2001 flu season. Many of those cases were linked to one flu vaccine manufacturer.

Although most cases happened that year, ORS does still happen. However, it’s considered a very rare reaction.

It’s safe for most people who have had ORS to get a flu vaccine again. Talk with your doctor first to make sure they don’t have any further concerns.

Most people with ORS and related pink eye do not need treatment. Symptoms go away with a few days of rest.

If you have any of the above symptoms of an allergic reaction, get medical treatment as soon as possible. An allergic reaction is a medical emergency that can result in death if not treated promptly.

In most cases, ORS does not require medical treatment. While many ORS symptoms overlap with those of an allergic reaction, ORS symptoms usually start later than an allergic reaction.

However, it’s always better to call a doctor if you’re not sure what type of reaction you’re having.

Many people experience side effects after flu vaccination. In most cases, these side effects are mild and go away within a few days.

After a flu shot, you might experience:

  • redness, swelling, or soreness at the injection site
  • muscle aches
  • headache
  • fever
  • nausea

Experts recommend almost everyone 6 months and older get a flu vaccine.

It’s especially important for pregnant people, children, and older adults to get a flu shot. These groups are at higher risk of developing complications from the flu.

Who should avoid vaccination?

There are some people who should not get a flu shot, including:

  • people allergic to any of the ingredients in the vaccine
  • babies younger than 6 months

If you’re allergic to eggs or have had Guillain-Barré syndrome, talk with your doctor before getting a flu vaccine. While you can still get one in most cases, your doctor may recommend certain kinds of vaccines or certain precautions.

You may still have questions about the effects a flu shot can have on your eyes. Here, we answer a few of the most frequently asked questions.

Can the flu shot cause red eyes?

If the flu shot causes red eyes, it’s a sign of an allergic reaction. Get medical treatment as soon as possible if your eyes become red after you get a flu shot.

Can the flu shot cause swollen eyes?

A flu shot can cause swollen eyes, but this is a sign of an allergic reaction. An allergic reaction to the flu shot is a medical emergency. Seek treatment immediately if you develop swollen eyes after getting a flu vaccine.

Can the flu shot cause other eye problems?

In rare cases, the flu shot has been associated with other eye problems, like swelling of the optic nerve and a condition called acute macular neuroretinopathy that can cause vision loss.

Can the flu itself cause pink eye?

The same virus that causes viral pink eye can also cause colds or respiratory infections. It is possible to spread the virus to your eyes by touching them after you sneeze or cough into your hands.

However, in most cases when you have both pink eye and the flu, they’re happening at the same time, rather than one causing the other.

If you notice red, swollen eyes after you get a flu shot, it could be an allergic reaction.

But if your other symptoms are minor or symptoms don’t start until a few hours after you get vaccinated, it could be a condition called oculo-respiratory syndrome (ORS).

ORS is a very rare reaction that usually doesn’t need treatment, but always call a doctor if you’re worried about your symptoms.