Nausea: causes, red flags and when to seek help

Nausea is generated in the brain, which receives signals from the gut, the inner ear, the bloodstream and the emotional centres. A stomach infection, a change in the balance system, a drug in the blood or a wave of anxiety can all trigger the same unpleasant sensation. This is why the feeling is so non-specific, and why the surrounding symptoms are the key to the cause.

The NHS says feeling sick is common and usually goes away on its own. Often the question is not what is wrong but how long it has gone on and what else is happening with it.

The NHS pairs diarrhoea or vomiting with norovirus or food poisoning, headache and a high temperature with an infection such as flu, heartburn or bloating after eating with acid reflux, headache and sensitivity to light or sound with migraine, and dizziness with labyrinthitis or vertigo. It lists pregnancy (morning sickness), motion sickness, anxiety, alcohol, medicines and recent surgery as other reasons.

Nausea can be the first or only sign of a heart attack, particularly in women and older adults, and can accompany raised pressure inside the skull, kidney failure, liver disease, high calcium and adrenal problems. Medicines are a very common hidden cause: antibiotics, painkillers, iron tablets, metformin, opioids and chemotherapy all provoke it. Persistent early-morning nausea without an obvious reason, particularly with headache or vomiting, is worth investigating.

Anxiety produces genuine nausea through the gut-brain connection, and so does withdrawing from alcohol or certain drugs. In pregnancy, nausea is usually mild morning sickness, but unrelenting vomiting that stops you keeping fluids down is a condition needing treatment.

The NHS says to call 999 if you suddenly feel sick and have chest pain that feels tight or heavy, pain that spreads to your arms, back, neck or jaw, or shortness of breath, as this could be a heart attack.

The NHS diarrhoea and vomiting guidance adds that you should call 999 or go to A&E if you or your child vomit blood or have vomit that looks like ground coffee, have green vomit as an adult, may have swallowed something poisonous, have a stiff neck and pain when looking at bright lights, have a sudden severe headache or sudden severe tummy ache, have blue, grey, pale or blotchy skin, lips or tongue, have severe difficulty breathing, or are confused or not responding as usual. It advises calling 111 if you keep being sick and cannot keep fluid down, have bloody diarrhoea, or have diarrhoea for more than 7 days or vomiting for more than 2 days.

People with diabetes who feel sick and are vomiting should seek emergency help promptly. Nausea with yellow skin or eyes, severe one-sided abdominal pain, a rigid abdomen or inability to pass wind also requires urgent assessment.

The NHS says the GP can look for the cause and suggest treatments, and may prescribe anti-sickness medicine if needed. Expect questions about how long you have felt sick, timing with meals and the day, vomiting, pain, bowel changes, weight loss, headache, vertigo, new medicines, alcohol, the possibility of pregnancy, and anything that has relieved or worsened it.

Examination covers hydration, blood pressure and pulse, the abdomen for tenderness, swelling or masses, and sometimes the nervous system and eyes. Urine or blood tests, a pregnancy test, an ECG if the heart could be involved, and sometimes an ultrasound or endoscopy follow where the picture is unclear.

The NHS suggests getting plenty of fresh air, distracting yourself with music or a film, taking regular sips of a cold drink, drinking ginger or peppermint tea, eating foods containing ginger such as ginger biscuits, and eating smaller, more frequent meals. It advises not eating or cooking strong-smelling food, avoiding hot, fried or greasy food, not eating too quickly, not having a large drink with meals, not lying down soon after eating and not wearing clothes tight around the waist or tummy.

If you are vomiting too, the NHS diarrhoea and vomiting page stresses having lots of fluids, taking small sips if you feel sick, and speaking to a pharmacist about signs of dehydration, such as dark smelly pee or peeing less than usual, or about oral rehydration powders.