Vomiting (being sick): causes, dehydration and red flags

Vomiting is a reflex coordinated by the brain, triggered by irritation of the stomach, signals from the gut and inner ear, chemicals in the blood, strong smells, pain, fear or pressure inside the skull. Because so many routes lead to the same reflex, the accompanying symptoms matter more than the vomiting itself.

The NHS says diarrhoea and vomiting are common in adults, children and babies, are often caused by a stomach bug and should stop in a few days. It says the advice is the same whether you have diarrhoea and vomiting together or separately, and that in adults and children vomiting usually stops in 1 or 2 days and diarrhoea in 5 to 7 days.

The NHS also lists, among other causes of vomiting, other infections such as a urinary tract infection and medicines. It names the most common causes of diarrhoea and vomiting as a stomach bug and food poisoning.

According to the NHS, you should stay at home and get plenty of rest, drink lots of fluids such as water or squash with small sips if you feel sick, eat when you feel able, and consider avoiding fatty or spicy foods. It advises not having fruit juice or fizzy drinks because they can make diarrhoea worse, and says paracetamol can be taken for discomfort.

Dehydration signs include dark, smelly pee or peeing less than usual. The NHS says to speak to a pharmacist if you have signs of dehydration, are an older person, have a weakened immune system, or have other health conditions that raise your risk. A pharmacist may recommend oral rehydration powder mixed with water. If you are still showing signs of dehydration after using oral rehydration sachets, the NHS says to call 111.

For nausea without vomiting the NHS suggests fresh air, distraction, regular sips of a cold drink, ginger or peppermint tea, ginger biscuits, smaller more frequent meals, avoiding strong-smelling, hot, fried or greasy food, not eating too quickly and not lying down soon after eating. It advises seeing a GP if you feel sick for more than a few days or often feel sick.

• Call 999 or go to A&E if you vomit blood or have vomit that looks like ground coffee.

• Call 999 or go to A&E if you may have swallowed something poisonous.

• Call 999 or go to A&E for vomiting with a stiff neck and pain looking at bright lights, a sudden severe headache, a sudden severe tummy ache, blue, grey, pale or blotchy skin, severe difficulty breathing, or confusion.

• Call 999 or go to A&E for green vomit in adults, as the NHS diarrhoea and vomiting page lists, which can suggest a blocked bowel.

• Call 999 if you suddenly feel sick with chest pain that feels tight or heavy, pain spreading to the arms, back, neck or jaw, or shortness of breath, which could be a heart attack.

• Call 999 or go to A&E if you have diabetes and are vomiting, as the NHS stomach ache advice states, because ketoacidosis can develop.

• Call 111 if you keep being sick and cannot keep fluid down, have bloody diarrhoea or bleeding from the bottom, vomiting for more than 2 days or diarrhoea for more than 7 days.

• After a head injury, repeated vomiting means calling 111 at least; the NHS lists being sick as a reason to get advice.

• See a GP if you feel sick and do not feel better in a few days, or often feel sick.

The history covers how long vomiting has lasted, how many times, what the vomit looks like (food, bile, blood, coffee grounds), whether there is diarrhoea, pain, fever, headache, neck stiffness, dizziness or chest pain, what you ate and who else is unwell, recent travel, new medicines, alcohol, the chance of pregnancy, diabetes, and whether you can pass urine, wind or stool.

The examination includes temperature, pulse, blood pressure, skin turgor and mouth for dehydration, the tummy for tenderness, distension and bowel sounds, and a neurological check if headache or confusion is present. Blood tests of kidney function, electrolytes and glucose are used when dehydration or serious illness is possible.

Recurrent vomiting has a different list of causes: gastric outlet problems, gastroparesis (slow stomach emptying), cyclic vomiting syndrome, migraine variants, medicine side effects, cannabis use, pregnancy including hyperemesis gravidarum, and in the stomach ulcer context the NHS lists feeling or being sick as a symptom. It notes that stomach ulcer symptoms with repeated vomiting, loss of appetite, early fullness or unintentional weight loss need urgent advice.

Investigations include blood tests, a gastroscopy to examine the stomach, imaging and gastric emptying studies, guided by the pattern. Treatment targets the cause and may include anti-sickness medicine; the NHS says a GP may prescribe anti-sickness medicine if needed.

Stomach bugs spread easily. The NHS says to stay off school or work until you have not been sick or had diarrhoea for at least 2 days, wash hands with soap and water frequently, wash clothing and bedding soiled with vomit separately on a hot wash, clean toilet seats, flush handles, taps, surfaces and door handles daily, avoid preparing food for others, not share towels or utensils, and avoid swimming pools until at least 48 hours after symptoms stop.