Severe pregnancy sickness (hyperemesis): a case-based approach

The case: unable to keep anything down

Imagine a woman at nine weeks pregnant who has been vomiting many times a day for over a week. She cannot keep down food or even sips of water, feels dizzy when she stands, and has lost weight. Her mouth is dry, she is passing only small amounts of dark urine, and she feels exhausted and low. In the teaching setting, this picture points to hyperemesis gravidarum rather than ordinary morning sickness. The key difference is severity: she is dehydrated and cannot maintain her fluids. The important teaching point is that this is not something to "push through" — it needs prompt medical assessment, because dehydration and weight loss in pregnancy can harm both mother and baby.

How it differs from morning sickness

Most pregnant people feel sick or vomit in early pregnancy, usually easing by around weeks 16 to 20. This is unpleasant but manageable — they can still keep down some food and fluids. Hyperemesis gravidarum is at the severe end. It causes prolonged, frequent vomiting so bad that a person cannot keep fluids down, loses more than a small amount of weight, and becomes dehydrated. It is thought to be linked to pregnancy hormones and is more common in first pregnancies and in twin or multiple pregnancies. It is a recognised medical condition, not weakness or fussiness. Understanding this difference matters, because severe sickness needs active treatment and monitoring rather than the reassurance and simple measures that suit mild sickness.

Red flags: dehydration and ketosis

The main dangers in severe pregnancy sickness are dehydration and ketosis. Warning signs that need urgent medical help include being unable to keep any fluids down for a day, passing very little or dark urine, or not passing urine for many hours. Feeling very dizzy or faint when standing, a fast heartbeat, severe weakness, or confusion are red flags. Ketosis — when the body burns fat for energy because it cannot get enough from food — can be detected as ketones in the urine and often makes a person feel very unwell. Vomiting blood, severe tummy pain, or a high temperature also need prompt assessment. If someone cannot keep down fluids or shows these signs, contact a midwife, GP or NHS 111 the same day, or attend hospital.

Why hospital care is sometimes needed

When someone with hyperemesis cannot keep fluids down and is dehydrated or has ketosis, they often need hospital care. In hospital, fluids can be given directly into a vein (a drip) to rehydrate them and correct any salt imbalances, which usually helps them feel much better. Anti-sickness treatment can be given by injection when tablets cannot be kept down. Blood and urine tests check hydration, salts and ketones, and rule out other causes. Some people are treated and sent home the same day; others stay longer or need repeated visits. There are safe anti-sickness medicines used in pregnancy, chosen carefully by clinicians. The aim is to stop the cycle of vomiting and dehydration so the person can recover and the pregnancy can continue safely.

Support, recovery and looking after yourself

Hyperemesis can be physically and emotionally draining, and feeling low or anxious is common — this is understandable and worth mentioning to your midwife or GP. Practical measures that may help between treatments include resting, eating little and often when able, plain bland foods, cold or dry foods that smell less, and taking small frequent sips of fluid. Ginger helps some people with milder sickness. Support at home matters, as does time off work if needed. Most people improve as pregnancy goes on, though some have symptoms for longer. Charities such as Pregnancy Sickness Support offer information and peer support. Anyone struggling should not suffer in silence — effective treatments exist, and repeated review helps adjust them until symptoms are under control.