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Pregnancy conditions

Hyperemesis gravidarum: symptoms, causes and treatment

Hyperemesis gravidarum is a severe form of pregnancy sickness in which nausea and vomiting are bad enough to stop you eating and drinking normally and to limit daily life. Unlike typical morning sickness, it can lead to dehydration and poor nutrition and may need hospital treatment. Call your midwife, GP or 111 if you cannot keep food or fluids down for 24 hours.

Last checked: 2026-10-11

Key facts

At a glance.

  • What it is

    The NHS says hyperemesis gravidarum is a severe form of pregnancy sickness that can be serious, with a chance of dehydration and malnutrition, and may need specialist treatment, sometimes in hospital.

  • How common

    The Royal College of Obstetricians and Gynaecologists (RCOG) says it affects between 0.3% and 3.6% of pregnant women.

  • Versus morning sickness

    Ordinary morning sickness usually clears up by weeks 16 to 20 and, the NHS says, does not put your baby at any increased risk. Hyperemesis is more severe and interferes with eating and drinking.

  • When to call

    The NHS says to call your midwife, GP or 111 if you are vomiting and cannot keep food or fluids down for 24 hours, or have very dark urine, have not peed in over 8 hours, vomit blood or have a high temperature.

  • Treatment

    The NHS says lifestyle changes come first, then anti-sickness medicine safe to use in pregnancy; severe cases may need an injection or a suppository, or hospital care.

  • Onset

    NICE CKS says nausea and vomiting usually begins between weeks 4 and 7, peaks between weeks 9 and 16, and resolves by weeks 16 to 20.

What is hyperemesis gravidarum?

The NHS says nausea and vomiting in pregnancy, often known as morning sickness, is very common in early pregnancy, can happen at any time of the day or night, and usually clears up by weeks 16 to 20. There is a chance of developing a severe form of pregnancy sickness called hyperemesis gravidarum, which can be serious: there is a chance you may not get enough fluids (dehydration) or enough nutrients from your diet (malnutrition), and you may need specialist treatment, sometimes in hospital.

NICE Clinical Knowledge Summaries (CKS) describes hyperemesis gravidarum as the most severe spectrum of symptoms: nausea and/or vomiting severe enough to cause an inability to eat and drink normally, and strongly limiting daily activities. Signs of dehydration contribute to the diagnosis.

The RCOG notes that the term "morning sickness" is not only inaccurate, because symptoms occur both before and after noon, but is felt by sufferers to trivialise the condition. It says hyperemesis gravidarum affects between 0.3% and 3.6% of pregnant women.

What are the symptoms of hyperemesis gravidarum?

NICE CKS says the key features are nausea and vomiting severe enough to cause an inability to eat and drink normally and which strongly limit daily activities, with signs of dehydration. The NHS lists these signs, any of which mean you should call your midwife, GP or NHS 111 if you are vomiting:

  • Very dark-coloured urine, or not having had a pee in more than 8 hours.

  • Being unable to keep food or fluids down for 24 hours.

  • Feeling very weak, dizzy or faint when standing up.

  • Tummy (abdominal) pain.

  • A high temperature.

  • Vomiting blood.

  • Weight loss.

When in pregnancy does it start and how long does it last?

NICE CKS says nausea and vomiting in pregnancy usually begins between the 4th and 7th weeks, peaks between the 9th and 16th weeks, and resolves by 16 to 20 weeks. It says onset of symptoms after 11 weeks of gestation usually suggests an alternative cause unrelated to pregnancy. The NHS says morning sickness usually clears up by weeks 16 to 20.

The pages used for this guide do not give a typical length of time for hyperemesis gravidarum specifically, which varies from person to person.

How is hyperemesis gravidarum treated?

The NHS says there is no hard and fast treatment that will work for everyone. If your morning sickness is not too bad, your GP or midwife will initially recommend lifestyle changes. If these do not work or symptoms are more severe, a doctor or midwife might recommend medicine.

Treatment steps for pregnancy sickness described by the NHS and NICE CKS
StepWhat it involves
Self-careGet plenty of rest; avoid foods or smells that make you feel sick; eat dry toast or a plain biscuit in the morning; eat small, frequent plain meals high in carbohydrate and low in fat; eat cold foods if the smell of hot meals makes you sick; sip fluids little and often.
Ginger and acupressureThe NHS says there is some evidence that ginger and acupressure on the wrist may help reduce nausea and vomiting. Check with your pharmacist before taking ginger supplements in pregnancy.
Anti-sickness medicineIf nausea and vomiting is severe and does not improve with lifestyle changes, your GP may recommend a short-term course of an antiemetic that is safe in pregnancy, often a type of antihistamine, usually as tablets.
Injection or suppositoryIf you have severe morning sickness (hyperemesis gravidarum), your doctor may suggest an injection or a medicine inserted into the bottom.
Hospital careNICE CKS says admission or referral is considered for moderate-to-severe symptoms with a complication, persistent symptoms despite primary care management, inability to tolerate oral medicines or fluids, clinical dehydration, or weight loss of more than 5% of body weight.

What increases the risk of severe pregnancy sickness?

The NHS says hormonal changes in the first 12 weeks of pregnancy are thought to be probably one of the causes of morning sickness. You may be more at risk if you are having twins or more, had severe sickness and vomiting in a previous pregnancy, tend to get motion sickness, have a history of migraine headaches, it runs in the family, you used to feel sick taking oestrogen contraceptives, it is your first pregnancy, or you are obese (a BMI of 30 or more).

NICE CKS lists increased placental mass (such as molar or multiple pregnancy), a first pregnancy, a history of hyperemesis gravidarum, a family history, and obesity.

What complications can severe sickness cause?

NICE CKS lists possible maternal complications if symptoms are severe: weight loss, electrolyte imbalance, acute kidney injury, nutritional and vitamin deficiencies, gastro-oesophageal reflux disease, venous thromboembolism and an impact on psychosocial functioning. It lists possible fetal complications with hyperemesis gravidarum including preterm delivery, low birthweight and small-for-gestational age.

The NHS says ordinary morning sickness does not put your baby at any increased risk. It also notes that urinary tract infections can sometimes cause nausea and vomiting.

Where can I get support?

Pregnancy Sickness Support, a UK charity established in 2002, describes itself as the only UK registered charity that provides emotional and practical support for people with hyperemesis gravidarum, including a national peer support network and evidence-based information. The NHS also points to the charity for tips for you and your partner on dealing with morning sickness.

NHS and private pathways in general terms

On the NHS, you can contact your midwife, GP or NHS 111 about severe sickness, and your maternity service can arrange assessment, fluids and medicines, including as a day-case or inpatient. Contact maternity services promptly if you cannot keep fluids down.

Private obstetric and early pregnancy services may offer assessment and treatment. Ask which anti-sickness medicines have been tried, what the plan is if you cannot keep fluids down, and who to call out of hours.

Frequently asked

Questions people ask.

Quick, plain-English answers to the questions we hear most.

  • What is hyperemesis gravidarum?

    A severe form of pregnancy sickness. NICE CKS describes nausea and/or vomiting severe enough to cause an inability to eat and drink normally and which strongly limits daily activities, with signs of dehydration. The NHS says it can be serious and may need hospital treatment.

  • How is hyperemesis different from morning sickness?

    The NHS says morning sickness is very common, usually clears up by weeks 16 to 20 and does not put your baby at any increased risk. Hyperemesis gravidarum is a severe form that can cause dehydration and malnutrition and may need specialist treatment, sometimes in hospital.

  • What are the symptoms of hyperemesis gravidarum?

    Severe nausea and vomiting, being unable to eat and drink normally, and signs of dehydration. The NHS says to call your midwife, GP or 111 if you have very dark urine, have not peed for over 8 hours, cannot keep food or fluids down for 24 hours, feel very weak or dizzy, have tummy pain, or vomit blood.

  • How common is hyperemesis gravidarum?

    The RCOG says it affects between 0.3% and 3.6% of pregnant women. It describes nausea and vomiting in pregnancy as affecting up to 90% of pregnant women, so hyperemesis is the severe end of a very common condition.

  • What causes hyperemesis gravidarum?

    The NHS says hormonal changes in the first 12 weeks are thought to be probably one of the causes of morning sickness. Risks include twins or more, severe sickness in a previous pregnancy, a first pregnancy, migraine, motion sickness, family history and obesity.

  • How is hyperemesis gravidarum treated?

    Lifestyle changes first, then anti-sickness medicine that is safe in pregnancy, usually antihistamine tablets. The NHS says severe cases may be offered an injection or a suppository. NICE CKS says hospital admission is considered for dehydration, persistent symptoms or an inability to tolerate fluids or medicines.

  • When should I contact my midwife or GP?

    The NHS says to call your midwife, GP or NHS 111 if you are vomiting and have very dark urine, have not peed for more than 8 hours, cannot keep food or fluids down for 24 hours, feel very weak, dizzy or faint, have tummy pain, a high temperature, vomit blood or have lost weight.

  • Does hyperemesis gravidarum harm the baby?

    The NHS says ordinary morning sickness does not put your baby at any increased risk. NICE CKS lists possible fetal complications of hyperemesis gravidarum including preterm delivery, low birthweight and small-for-gestational age, which is why severe symptoms need medical review.

  • Can ginger help with pregnancy sickness?

    The NHS says there is some evidence that eating or drinking foods or drinks containing ginger may help reduce nausea and vomiting, but to check with your pharmacist before taking ginger supplements in pregnancy. It is unlikely to be enough on its own for severe sickness.

  • When does pregnancy sickness usually start and stop?

    NICE CKS says it usually begins between weeks 4 and 7, peaks between weeks 9 and 16 and resolves by weeks 16 to 20. Onset after 11 weeks of pregnancy usually suggests another cause. The NHS says morning sickness usually clears up by weeks 16 to 20.

Where this comes from

Sources and checking.

This guide is for information, not medical advice.

Your GP or consultant knows your history and can tell you which parts apply to you. If your symptoms are severe, rapidly worsening, or come with red-flag features, seek urgent medical care. Figures and availability change, so treat them as a guide and confirm with the provider.

Published 2026-10-11, next review 2027-10-11.

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