Experiencing blurred vision and a headache at the same time can be frightening, especially the first time it happens.

Blurred vision can affect one or both eyes. It can cause your vision to be cloudy, dim, or even peppered with shapes and colors, making it difficult to see.

Certain injuries and medical conditions can cause blurred vision and headache, but migraine is the most common cause.

The following conditions can cause blurred vision and headache at the same time.

Migraine

Migraine is a headache disorder that affects over 39 million people in the United States. Of these, 28 million are women. Migraine causes moderate to severe pain that’s often made worse by light, sound, or movement.

Aura is another word for blurred vision that accompanies a migraine. Other symptoms of aura include blind spots, temporary vision loss, and seeing bright flashing lights.

Migraine pain typically lasts three or four days. Common symptoms include nausea and vomiting.

Traumatic brain injury

Traumatic brain injury (TBI) is a type of head injury that causes damage to the brain. There are different types of brain injuries, such as concussions and skull fractures. Falls, motor vehicle accidents, and sports injuries are common causes of TBI.

Symptoms of TBI can range from mild to severe, depending on the extent of the damage. Other symptoms include:

Low blood sugar

Low blood sugar, or hypoglycemia, often occurs in people who have diabetes. However, there are other things that can cause your blood sugar to drop, including fasting, certain medications, and consuming too much alcohol.

Signs and symptoms of low blood sugar include:

Symptoms become more severe as hypoglycemia worsens. If untreated, hypoglycemia can lead to seizures and loss of consciousness.

Carbon monoxide poisoning

Carbon monoxide poisoning is an emergency that requires immediate medical care. It results from a buildup of carbon monoxide in your bloodstream. Carbon monoxide is an odorless, colorless gas produced by burning wood, gas, propane, or other fuel.

Apart from blurred vision and headache, carbon monoxide poisoning may cause:

Pseudotumor cerebri

Pseudotumor cerebri, also called idiopathic intracranial hypertension, is a condition in which cerebrospinal fluid builds up around the brain, increasing pressure.

The pressure causes headaches that are usually felt at the back of the head and are worse at night or upon wakening. It can also cause vision problems, such as blurred or double vision.

Other symptoms may include:

  • dizziness
  • persistent ringing in the ears
  • depression
  • nausea and/or vomiting

Temporal arteritis

Temporal arteritis is an inflammation of the temporal arteries, which are the blood vessels near the temples. These blood vessels supply blood from your heart to your scalp. When they become inflamed, they restrict blood flow and can cause permanent damage to your eyesight.

A throbbing, persistent headache on one or both sides of your head is the most common symptom. Blurred vision or brief vision loss is also common.

Other symptoms may include:

  • jaw pain that worsens with chewing
  • scalp or temple tenderness
  • muscle aches
  • fatigue
  • fever

High or low blood pressure

Changes in your blood pressure can also cause blurred vision and headache.

High blood pressure

High blood pressure, also called hypertension, happens when your blood pressure increases above healthy levels. High blood pressure typically develops over years and without any symptoms.

Some people experience headaches, nosebleeds, and shortness of breath with high blood pressure. Over time, it can cause permanent and serious damage to the retina’s blood vessels. This can lead to retinopathy, which causes blurred vision and may result in blindness.

Low blood pressure

Low blood pressure, or hypotension, is blood pressure that has dropped below healthy levels. It can be caused by dehydration, certain medical conditions and medications, and surgery.

It can cause dizziness, blurred vision, headache, and fainting. Shock is a serious possible complication of very low blood pressure that requires emergency medical treatment.

Stroke

A stroke is a medical emergency that occurs when the blood supply to an area of your brain is interrupted, depriving your brain tissue of oxygen. There are different types of strokes, though the ischemic stroke is the most common.

Stroke symptoms may include:

  • a sudden and severe headache
  • trouble speaking or understanding
  • blurred, double, or blackened vision
  • numbness or paralysis of the face, arm, or leg
  • trouble walking

Diagnosing the cause of blurred vision and headache may require a review of your medical history and a number of different tests. These tests may include:

Treatment will depend on the cause of your blurred vision and headache.

You may not require any medical treatment if your symptoms were a one-time occurrence caused by low blood sugar from going too long without eating. Consuming a fast-acting carbohydrate, such as fruit juice or candy can increase your blood sugar levels.

Carbon monoxide poisoning is treated with oxygen, either through a mask or placement in a hyperbaric oxygen chamber.

Depending on the cause, treatment may include:

Blurred vision and headache together can indicate a serious medical condition. If your symptoms are mild and only last for a short period or you’ve been diagnosed with migraine, see your doctor.

When to go to the ER or call 911

Go to the nearest emergency room or call 911 if you or someone else suffers a head injury or experiences blurred vision and headache — especially if severe or sudden — with any of the following:

Blurred vision and headache are most often caused by migraine, but they can also be caused by other serious conditions. If you’re concerned about your symptoms, make an appointment to see your doctor.

If your symptoms began after a head injury, are sudden and severe, or accompanied by symptoms of a stroke, such as difficulty speaking and confusion, seek emergency medical care.