Causes of nausea

Feeling sick - nausea - or being sick is a miserable experience. We tend to think of feeling sick as being a gut problem, but there are lots of other reasons. You have a 'vomiting centre' in your brain and it's often here that the issue lies. In addition, your inner ears play an important role in balance, and an issue affecting the inner ear can often lead to vomiting or feeling sick in addition to dizziness. The other symptoms that go along with feeling or being sick often give clues to the cause.

Authored by Dr Sarah Jarvis MBE ·
Reviewed by Dr Krishna Vakharia

17-Mar-23 · 7 mins read

What are the causes of nausea and vomiting?

The medical term for feeling sick is nausea, and it's very common. The causes can largely be split into gut problems and issues elsewhere that affect the vomiting centre in the brain.

Gut causes

When you drink and eat food, it passes down your gullet (oesophagus) into your stomach. Here the process of digestion starts, and stomach contents are passed on to the intestines. Vomiting happens when your stomach contents travel back up your gullet to your mouth instead.

Inflammation of the gut lining makes it irritable and prone to contracting abnormally. This can cause you to experience nausea, vomiting, diarrhoea, and tummy pain - which is often colicky. Gut lining inflammation (gastroenteritis) can happen in both adults and children. Food poisoning and excess alcohol intake can also cause this.

While tummy bugs usually settle on their own, older people - as well as young children and babies - can be more prone to signs of dehydration.

Other gut-related causes of nausea and vomiting, which are often accompanied by tummy pain, include:

Stomach ulcers.
Gastro-oesophageal reflux disease (GORD) - the one-way valve between the bottom of the gullet and the top of the stomach is weakened, allowing food to travel backwards.
Gallstone-related problems.
Appendicitis.
Blockage of the bowel - called bowel obstruction. This can be due to bowel cancer, hernia, scar tissue or narrowing of the bowel due to Crohn's disease or diverticulitis.
Inflammation of the pancreas - called pancreatitis.

Severe liver disease such as cirrhosis and kidney issues - including kidney stones and chronic kidney diease - can also lead to nausea and vomiting. You can find out more about the other symptoms of these conditions in our information leaflets.

Ear problems

The balance mechanisms in your inner ears sense head movements and send messages to your brain to tell it your position. Sometimes these balance mechanisms or the nerves that connect it to your brain become inflamed. This can lead to a combination of nausea and vomiting along with vertigo - dizziness where if feels as if the room is spinning. You may have other symptoms of a cold or, less often, ear pain.

Viral labyrinthitis - The most frequent cause of this type of nausea is a virus infection. Often called viral labyrinthitis, it can be debilitating but lying completely still usually settles the symptoms and they tend to get better on their own over a few days or weeks. Your doctor can prescribe medicine to help the nausea if needed.

If you have vertigo and/or being sick accompanied by sudden deafness in one ear, you should always seek medical help quickly.

Meniere's disease - A condition called Meniere's disease leads to attacks of vertigo, hearing loss and noises in the ear (tinnitus) - nausea and vomiting can sometimes occur alongside this. Episodes last on average 2-4 hours and can come out of the blue or in clusters of several attacks in short succession. Speak to your doctor if you get this combination of symptoms -medication to treat or reduce the frequency of attacks may be recommended.

Travel sickness

Travel, or motion sickness, is also a frequent cause of nausea and vomiting, especially in children. Repeated movements send multiple messages to your brain. If the messages from your eyes are different to those from your inner ears, your brain can become confused, leading to motion sickness. It's often made worse by strong smells, or reading a book or a map.

How can I avoid travel sickness?

If you suffer from motion sickness, avoid heavy meals before travelling. Breathe in fresh air if you can, and sit in the front of the car, on deck in the middle of a boat or on an airplane seat over the wing. Don't try to read, watch a film or look at things inside the car. Instead, close your eyes and try to sleep or focus on the horizon. Avoid alcohol and spicy or fatty food, taking sips of water instead. Slow, steady breathing and ginger - ginger ale or in a biscuit - may help. Your pharmacist may be able to advise on medicine if it's very troublesome.

Migraines

The severe headache of migraine can also be accompanied by feeling or being sick. It's thought that messages in the lower part of the brain, called the brainstem, are disrupted during migraines. This part of the brain processes pain and other sensations and it may be why this type of headache is so commonly linked with nausea and vomiting. People with migraine are prone to motion sickness as well.

The headache of migraine is often, but not always, on one side of your head, and you're likely to feel very unwell with it. Episodes can last from four hours to three days. If you have frequent migraines, your doctor may recommend regular medication to make them less frequent.

Medicines

In addition, nausea and vomiting can be a side effect of several medications. This is sometimes because they irritate the stomach lining, but they can also affect parts of the brain that control vomiting. Common causes include:

Cancer treatments - such as chemotherapy.
Antibiotics - especially erythromycin.
Anti-inflammatory medicines - including ibuprofen, naproxen and aspirin.
Strong opioid painkillers - such as strong codeine or morphine.
Some vitamin and mineral supplements - such as iron.
Some antidepressants.

If you think your symptoms may be due to medication, speak to your pharmacist. Simple measures such as taking medication with food or adjusting the timing of your medicine may help.

Morning sickness

Women often have nausea and vomiting during pregnancy, especially in the first three months. Traditionally called morning sickness, many pregnant women are all too aware that it can be morning, noon and night sickness. Morning sickness is probably largely down to hormonal changes and in a small number of cases it can lead to severe dehydration.

Rare but important

There are some serious medical conditions which can lead to nausea and vomiting, although you will almost always have other symptoms as well. Possible serious causes include:

Meningitis.
Brain tumours.
Head injuries.
Hypercalcaemia - raised levels of calcium in your blood.
Diabetes - especially if it leads to very high levels of blood glucose. For instance, diabetic ketoacidosis, which usually affects people with type 1 diabetes or those taking insulin for type 2 diabetes, can lead to severe tiredness, headache, rapid breathing, dry mouth, and even collapse and loss of consciousness as well as nausea and vomiting.

When should I worry about nausea and vomiting?

Doctors always check for 'red flags' with sickness that could mean a serious underlying problem. Always seek medical help if you're experiencing nausea or vomiting along with:

Weight loss for no apparent reason.
Severe tummy pain.
Confusion or loss of consciousness.
Blood or yellow bile in your vomit.
Fever, headache or stiff neck, sensitivity to light or a rash that doesn't fade when you press a glass against it.
Persistent or worsening vomiting that goes on for more than 48 hours.
Bringing up blood or bile.
Have severe tummy pain or unexplained weight loss or change in your bowel habit.
Have a high fever or feel weak or confused.

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With thanks to 'My Weekly' magazine where this article was originally published.

Rare but important

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