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Spewing 101: Why am I vomiting?

Monday 23 July 2018

wooden mannequin hugging toilet bowl indicating they're vomiting
Everyone has experienced vomiting in their lives, but how much do you know about it?

Whether it was a bout of gastro, morning sickness, a migraine, the dreaded hangover, or something more serious, we have all experienced vomiting in our lives. Vomiting is a common symptom and can be caused by dietary or lifestyle factors, or the body’s reaction to infections, stomach irritations and medications. Vomiting can also be caused by long-term conditions such as diabetes or cancer-related treatments.

While vomiting can be relieving for the body, it may cause some adverse reactions. Let’s take a look at why you vomit and how it affects your body, what steps to take that will help get you back on your feet and when to seek medical help.

What is vomiting?

Vomiting is the body’s way of protecting you from threats. When it detects a harmful substance or something irritating, your body actually thinks you’re being poisoned. The body’s natural reaction is to rid the body of that threat, causing it to expel the contents of the stomach.

There are many causes of vomiting. From the effects of a rough night with your mates, to pregnancy, motion sickness, and all the infections, viruses and medications in between. Vomiting can be a one-off caused by something you ate or something you did, while acute vomiting for conditions like food poisoning or gastro can last a few hours to a few days. Vomiting for more than a few days, or experiencing other symptoms alongside the vomiting, could mean there is a serious underlying condition and you may need medical assistance.

young man holding back his hair while vomiting into a toilet in pub

How does vomiting affect my body?


When a vomit is looming, a signal is sent to an area of the brain called the chemoreceptor trigger zone, or CTZ. The CTZ receives this information and determines if the threat warrants vomiting. The CTZ then communicates to other areas of the body to start the domino effect for vomiting.

Before you vomit you may feel nauseous, become pale, have a cold sweat, and have an increased heart rate. Your mouth will also produce extra saliva to protect your teeth from the incoming stomach acid.


As your body prepares to vomit, the major muscles in between the neck and abdomen – the diaphragm, chest wall and the abdominal muscles – all contract at the same time. This puts pressure on the stomach, forcing the contents in the stomach up the throat and through your mouth.

Generally, a few contractions occur before vomiting, causing dry heaving. As the contractions continue, the stomach contents are up, up and away! To protect you from choking, the throat has a flap called the epiglottis which closes to stop any vomit getting into the windpipe and lungs.


Vomiting causes the body to lose fluids that contain salts and minerals called electrolytes. While one vomit alone is not likely to cause adverse reactions, multiple vomits in a short period of time can quickly lead to dehydration, particularly in babies and children, and an electrolyte imbalance. Electrolytes are vital for your body to perform normal functions like regulating your heartbeat, signalling your nerves, and moving your muscles. When the balance is disturbed, you’ll usually feel miserable until the electrolytes are replaced with fluids.

Prolonged vomiting can also cause damage to enamel on your teeth because the strength of stomach acid. Additionally, it can be difficult to replace essential nutrients when you’re continuously vomiting, which can cause malnourishment. Over time, this can lead to your body not functioning properly, lowered immunity and unintended weight loss.

A glass of water with a man vomiting in the background

What should I do to look after myself after vomiting?

There are some things you can do to help you feel better after vomiting:

  • neutralise any stomach acid left in your mouth – rinse with water or fluoridated mouth wash (don’t brush your teeth as this can damage enamel)
  • replace fluids and electrolytes at the first sign of vomiting – mixing oral rehydration solutions in water will help replace the lost electrolytes
  • try eating bland foods, like crackers, rice or dry toast
  • avoid sugary, alcoholic or caffeinated drinks – these will only make your symptoms worse
  • rest.

When should I seek help for vomiting?

Vomiting is a symptom so it’s important to treat the underlying condition that is causing it. For one-off and acute vomiting, the illness will usually resolve itself without medical treatment. If you have other symptoms with your vomiting, it could mean something more serious.

Call Triple Zero (000) if you are vomiting and also have:

  • chest pain
  • severe abdominal pain or cramping
  • high fever and stiff neck
  • blurred vision
  • confusion
  • poo in the vomit
  • bleeding from your rectum
  • swallowed something poisonous.

See your doctor if you have:

  • been vomiting for more than two days
  • a severe headache
  • dehydration
  • green or blood in the vomit
  • stomach pain
  • diabetes, especially if you take insulin.

Babies and children must be monitored closely while they are unwell as their condition can go downhill quickly if dehydration occurs.

If you are concerned about your health or the health of a loved one, call 13 HEALTH (13 43 25 84) to speak with a registered nurse or see your doctor.

Related information

How to look after your kids when gastro strikes

Last updated: 20 August 2018