A wheeze is a high-pitched, continuous whistling sound heard during breathing. Though it often happens when you exhale, wheezing can also occur when you inhale (inspiration).

Wheezing usually is a sign of narrowing airways or a blockage in the vocal cords. However, there are other causes of this condition. If you’re wheezing and also find it difficult to breathe, seek immediate medical attention.

There are two main types of wheezing — inspiratory (when you inhale) and expiratory (when you exhale).

It’s easier to hear expiratory wheezing because your airways narrow more during this breathing phase. Sometimes, expiratory wheezing is loud enough to hear on its own. Expiratory wheezing alone often indicates a mild airway obstruction.

Inspiratory wheezing occurs when you inhale. In some people with asthma, you can only hear wheezing during the inspiratory phase.

If you’re wheezing when you exhale and inhale, you could have a more severe breathing issue. To diagnose what type of wheezing you have, your doctor will use a stethoscope to hear if it’s loudest over your lungs or neck.

Inspiratory wheezing often accompanies expiratory wheezing when heard over the lungs, specifically in acute asthma. However, if inspiratory wheezing or stridor is heard over the neck, that could be an indication of a serious upper airway obstruction.

Wheezing is often caused by inflammation in your throat or lungs. The whistling sound occurs when air is pushed through narrowed airways.

Wheezing is most associated with asthma. However, it may also be a symptom of other respiratory issues, infections, and associated conditions including:

More severe causes of inspiratory and expiratory wheezing include:

Your doctor may use a chest X-ray to diagnose what’s causing your wheezing when it occurs for the first time. You may also be asked to perform a breathing test.

If you begin to experience dizziness, chest pain, or difficulty breathing alongside your wheezing symptom, you should call 911.

Treating wheezing ultimately depends on the underlying cause. If your wheezing is severe, your doctors may give you an oxygen mask to steady your breathing and bronchodilators to help open your airways. In this case, they may recommend you stay at the hospital overnight.

If inflammation is causing your wheezing, your doctor will prescribe anti-inflammatory medications like steroids to reduce swelling and open your airways for easier breathing.

If your wheezing is caused by an infection, you may be prescribed antibiotics to treat the condition and associated symptoms.

If you’re diagnosed with asthma, your doctor will prescribe you medication, usually an inhaler.

Wheezing can occur when you inhale and exhale. Though asthma and inflammation are common causes of this symptom, wheezing can be a sign of a more serious condition.

If your wheezing is accompanied with breathing difficulties, seek immediate medical attention. Discuss your concerns with your doctor to receive a proper diagnosis and the best treatment for your condition.