A stroke is a serious emergency that requires immediate medical attention. Strokes are life-threatening and can cause permanent disability, so seek help right away if you suspect that a loved one is having a stroke.

The most common type of stroke is an ischemic stroke. These occur when a blood clot or mass blocks blood flow to the brain. The brain needs blood and oxygen to function properly. When there’s not enough blood flow, cells begin to die. This can lead to permanent brain damage.

The longer it takes to recognize signs of a stroke and get to the hospital, the greater the likelihood of permanent disability. Early action and intervention is extremely important and can result in the best possible outcome.

If you’re unfamiliar with stroke signs and symptoms, here is what you need to watch for.

A stroke can affect one’s ability to express and understand language. If a loved one is experiencing a stroke, they may have difficulty speaking or explaining themselves. They may struggle to find the right words, or their words may be slurred or sound choppy. As you speak with this person, they may also seem confused and unable to comprehend what you’re saying.

Strokes can occur on one side of the brain or both sides of the brain. During a stroke, some individuals experience muscle weakness or paralysis. If you look at this person, one side of their face may appear droopy. The change in appearance may be barely noticeable, so ask the person to smile. If they’re unable to form a smile on one side of their face, this may indicate a stroke.

Also, ask the person to raise both of their arms. If they are unable to raise one of their arms due to numbness, weakness, or paralysis, seek medical attention. A person having a stroke may also stumble and fall due to weakness or paralysis on one side of their body.

Keep in mind that their limbs may not go completely numb. Instead, they may complain of a pins and needles sensation. This can occur with nerve problems as well, but it can also be a sign of stroke — especially when the sensation is widespread on one side of the body.

Strokes affect people differently. Some people are unable to speak or communicate, but they can walk. On the other hand, another person having a stroke may be able to talk normally, yet they’re unable to walk or stand because of poor coordination or weakness in one leg. If a loved one is suddenly unable to maintain their balance or walk as they normally do, seek immediate help.

If you suspect that a loved one is having a stroke, ask about any changes in their vision. A stroke may cause blurry vision or double vision, or the person may completely lose vision in one or both eyes.

Sometimes, a stroke can mimic a bad headache. Because of this, some people don’t seek medical attention right away. They may assume they’re having a migraine and need to rest.

Never ignore a sudden, severe headache, especially if the headache is accompanied by vomiting, dizziness, or drifting in and out of consciousness. If having a stroke, the person may describe the headache as different or more intense than headaches they’ve had in the past. A headache caused by a stroke will also come on suddenly without a known reason.

It’s important to note that while the above symptoms can occur with other conditions, one telltale sign of a stroke is that symptoms occur suddenly.

A stroke is unpredictable and can occur without warning. A person could be laughing and talking one minute, and unable to talk or stand on their own the next minute. If anything seems out of the ordinary with your loved one, call for help immediately rather than driving the person to the hospital. For every minute that their brain doesn’t receive adequate blood flow and oxygen, the ability to fully regain their speech, memory, and movement decreases.