Home
Health Encyclopedia
Print
Search Clinical Content Search Health Library
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A-Z Listings

Near-Fainting: Vagal Reaction

Fainting (syncope) is passing out. It's a temporary loss of consciousness. Near-fainting is feeling like you are going to faint. But you don't lose consciousness. Fainting and near-fainting can be caused by a vagal reaction (or overstimulation of the vagus nerve). This is something you can't control. It's the body's involuntary response to a physical or emotional stress.

This reaction causes a sudden drop in your blood pressure or a slowed heart rate. As a result, not enough blood goes to your brain. Lying down often stops the reaction very quickly.

These are symptoms of near-fainting:

  • Feeling lightheaded or like you are going to faint

  • Weak pulse

  • Upset stomach (nausea)

  • Sweating

  • Blurred vision or feeling like your vision is "blacking out"

  • Trouble breathing

  • Cool and moist skin

Causes for near-fainting include:

  • Sudden emotional stress such as fear, pain, panic, or the sight of blood

  • Straining or overexertion, straining while using the toilet, coughing, or sneezing

  • Standing up too quickly or standing up for too long a time

  • Pregnancy

  • Some medicines

  • Fluid loss (dehydration)

Home care

These tips will help you care for yourself at home:

  • Rest today and go back to your normal activities when you feel back to normal.

  • If you get lightheaded or dizzy, lie down right away. Put your legs up so they are higher than your heart.

  • If you are sitting down and feel faint, don't stand up. This may make the feeling worse.

  • Drink plenty of fluids, and don't skip meals.

  • Don't stand for long periods or stay in hot places.

  • Do what you can to prevent constipation. If you bear down a lot when trying to poop (have a bowel movement), this can trigger a vagal response.

Check with your healthcare provider to see if you need tests, such as a tilt-table test, heart rhythm monitoring, or blood tests. Review the medicines you take with your provider and pharmacist. Make sure the symptoms you have are not a side effect of a medicine.

Follow-up care

Follow up with your healthcare provider, or as advised. 

If you have frequent episodes of near-fainting or vagal reactions, be careful about activities such as driving. You could harm yourself or others if you were to faint. Don't drive or operate heavy machinery if you are feeling like you may faint.

Call 911

Call 911 if any of these occur:

  • Another fainting spell not explained by the common causes listed above

  • Chest, arm, neck, jaw, back, or belly (abdominal) pain

  • Shortness of breath

  • Weakness, tingling, or numbness in 1 side of the face, or 1 arm or leg

  • Slurred speech, confusion, or trouble walking or seeing

  • Seizure

  • Blood in vomit or poop (black or red color)

When to get medical care

Call your healthcare provider right away if you sometimes have mild lightheadedness, especially when standing up.

Online Medical Reviewer: Anne Clayton APRN
Online Medical Reviewer: Stacey Wojcik MBA BSN RN
Online Medical Reviewer: Steven Kang MD
Date Last Reviewed: 9/1/2022
© 2000-2024 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.