You probably understand that sneezing (also called sternutation) is your body’s way of expelling foreign material, like dust or pollen, from the respiratory tract.

There’s also some evidence that the high air pressure in your mouth associated with sneezing also causes your brain to tell nerves in your nose to produce extra mucus in your nose. This extra mucus helps keep foreign substances from making it into your lungs.

You may have heard that your heart skips a beat when you sneeze, but that’s a myth.

Electrical signals that control your heart rate aren’t affected by the physiological changes that happen when you sneeze. But the heart may get delayed for a second or two before resuming its regular rhythm.

There’s no need to worry — your heart gets right back on track shortly after a sneeze without causing any threats to your health.

We’ll go over the details of what happens to your heart when you sneeze, talk about the extremely rare case when a sneeze can knock you out, and the common causes of sneezing.

Again, your heart doesn’t stop when you sneeze — it may get briefly thrown off its rhythm. Here’s a breakdown of what that means:

  1. Right before you sneeze, you inhale deeply. This builds up extra pressure in the chest, slows down blood flowing to your heart, lowers your blood pressure, and raises your beats per minute (BPM).
  2. Your throat closes up. You may be familiar with the sensation of your throat feeling blocked right before you cough or sneeze. This allows your abdominal cavity to maintain the intrathoracic pressure that’s already built up to help expel all that air in the final step of a sneeze.
  3. You suddenly and violently exhale. When you finally sneeze, all the pressure that’s built up in your abdomen releases quickly. This speeds up blood flowing back to your heart, raises your blood pressure, and lowers your BPM all at once.

This sudden pressure and blood flow change results in a brief interruption in your heartbeat as your heart compensates for the rapid increase in blood pressure.

The vagus nerve, which winds all the way from your brain to your large intestine, is also involved in this cardiac interruption.

One of the nerve’s most important functions is to reduce your heart rate. When it’s stimulated by a sneeze, its immediate response is to lower the heart rate. In combination with the decrease in heart BPM and increase in blood pressure, the heart gets thrown off its rhythm for a second.

Sneeze syncope (the medical name for fainting) is an uncommon condition in which the decrease in heart rate or blood pressure that happens during a sneeze can knock you out.

Sneeze syncope is rarely reported — the last known documentation of someone who actually passed out from a sneeze dates back to a 2014 case study in Case Reports in Neurological Medicine.

Sneeze syncope isn’t a serious condition by itself. But a 2006 case study found that a woman who had glaucoma was taking beta-blocker eye drops that were delaying electrical signals in her heart and resulting in a loss of consciousness. Once she stopped taking the eye drops, she stopped fainting after sneezing.

And in the 2014 case study, a 50-year-old man experienced syncope because of a tumor on one of his heart valves. After the tumor was removed, the man no longer had any episodes of fainting or other neurological issues after sneezing.

In most cases, sneeze syncope is caused by an underlying condition. Another such condition is mitral valve prolapse — this happens when the valve becomes weak and doesn’t seal in blood properly, which can lead to irregular heart rhythms that worsen when you sneeze and cause pressure changes.

Many cases have to do with your heart. See a doctor first if you’re having episodes of fainting after sneezing, then get a referral to a cardiac specialist for further testing of your heart rate.

Sneezing is always caused by your body trying to remove foreign substances from somewhere in your respiratory tract (the nose, throat, or lungs). The most common, harmless cause is simply inhaling something that irritates your respiratory tract, such as dust, spices, pollen, or mold.

But sneezing can have several medical causes, some of which may need treatment:

  • Common cold. Colds are caused by viral infections of your respiratory tract. They aren’t usually serious, and symptoms go away on their own with rest and hydration.
  • Allergic rhinitis. This condition is an inflammation of your nasal passages in response to an allergen that you inhale, resulting in sneezing, coughing, and itching. It’s not necessarily serious, but over time it can cause headaches, sinus infections, or even asthma symptoms. Use an antihistamine like cetirizine (Zyrtec) or loratadine (Claritin) to control symptoms, and see a doctor if your symptoms don’t get any better over time with treatment.
  • Influenza (flu): The flu is caused by a viral infection that can also cause a stuffy nose, body aches, and fatigue. See a doctor as soon as possible if you think you have the flu, as untreated flu infections can cause more serious complications.

When you sneeze, your heart rhythm is thrown off and the next beat is delayed, but your heart beat doesn’t fully stop. This isn’t a serious condition.

But see a doctor if you notice any abnormal symptoms after you sneeze, such as dizziness, nausea, or fainting. These can all indicate conditions that may need treatment to prevent long-term complications, especially those related to your heart.