What are the Most Common Causes of Nausea and Fainting?

Nausea refers to a feeling of queasiness and vertigo or the feeling that a person has before vomiting. Fainting is when a person unexpectedly loses consciousness for a short period of time. Among the conditions that cause nausea and fainting are vasovagal syncope and carbon monoxide poisoning.

Vasovagal syncope, also called the "common faint" is the most common form of fainting. In addition to nausea and fainting, symptoms of vasovagal syncope include cold sweat, clammy sweat, and paleness. Other symptoms can include blurry vision, yawning, and lightheadedness.

A "shock to the system" that impacts the part of nervous system that affects heart rate and blood pressure can cause vasovagal syncope. Ultimately, this decreases the amount of blood flowing to the brain, which leads to a short period of unconsciousness until the body readjusts. Shocks that can lead to vasovagal syncope can include emotional reactions to the sight of blood or injuries, physical factors like standing with locked legs for too long, and environmental causes such as standing in a hot, crowded room with little ventilation for an extended period of time. In addition, medical conditions including heart disorders, low blood sugar, also called hypoglycemia, or dehydration can lead to vasovagal syncope.


Common faints typically do not require medical attention. If the fainting spell is the first incident, the victim should make an appointment to see a physician to make sure that the vasovagal syncope incident was not related to an underlying medical condition. Treatments will depend on what, if any, underlying illness led to the fainting spell.

Carbon monoxide poisoning is the most common form of accidental poisoning that leads to death in the United States. Detecting carbon monoxide, a gas, is difficult as carbon monoxide lacks a taste, a color, or a smell. Methods of preventing carbon monoxide poisoning include installing carbon monoxide detectors, maintaining and using gas appliances as directed by the appliances' manufacturers, and always opening the garage door before starting a vehicle. In addition, people should only purchase gas appliances that have been approved by organizations such as American Gas Association or Underwriters' Laboratories.

Nausea and fainting are two symptoms of carbon monoxide poisoning. In addition to nausea and fainting, a person who is experiencing carbon monoxide poisoning may be confused, may vomit, or may experience chest pains. People who are drunk or asleep may succumb to carbon monoxide poisoning without experiencing any of the symptoms related to the poisoning. In addition, people who have already lost consciousness may remain unconscious until they die.

Carbon monoxide poisoning victims need oxygen. In a hospital situation, pure oxygen may be supplied to the patient via a mask over the nose and mouth. Some cases require treatments in a hyperbaric chamber, where the whole body is supplied oxygen under pressurized conditions.


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Post 2

Women with severe morning sickness can also have fainting and nausea. My cousin had both when she was pregnant with her second child. Her husband found her on the floor where she had fainted. She had to go to the hospital for fluids and IV nourishment since she couldn't keep anything down. Her fainting was probably from not eating and dehydration. Her OB/GYN said she had one of the worst cases of pregnancy sickness he'd ever seen. She was sick most of her pregnancy. She was on the same anti-nausea meds that chemotherapy patients get. It was pretty bad.

Post 1

Heat stroke can also cause nausea and fainting. This is especially important for people working outside to remember.

Drink water, get in the shade occasionally, and stop working if you feel light-headed or nauseated. This can head off heat stroke before it really gets serious and lands you in the hospital.

I had mild heat exhaustion once, and it took me about a day and a half before I felt right again. I was nauseated for several hours and also felt light-headed. I drank a quart of sports drink and didn't eat anything until the next day. It was a terrible feeling.

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