Hyperemesis Gravidarum: When Sickness Is Not Normal

When to call

This section is first because hyperemesis is chronically under-treated, and the delay usually happens at the point of asking.

Contact your GP or maternity unit urgently today if, as the HSE sets out, you have not been able to keep any fluids down for 24 hours, you are vomiting many times a day, you feel dizzy, you are losing weight, or your urine has become dark, is coming less often, or you have not passed any for 8 hours or more.

The NHS puts it more simply: contact your midwife, GP or hospital if you are vomiting frequently and cannot keep food down, because early treatment prevents dehydration.

Ask for hospital assessment if you cannot keep anti-sickness tablets down. RCOG's guideline says inpatient care should be considered if there is at least one of: continued nausea and vomiting with an inability to keep down oral antiemetics; continued nausea and vomiting with clinical dehydration or weight loss greater than 5% of body weight despite oral antiemetics; or a confirmed or suspected other condition alongside it, such as a urinary tract infection you cannot take oral antibiotics for.

Treat as an emergency — call your local emergency number (999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, or 111 in New Zealand) — if there is confusion, abnormal eye movements or unsteadiness. RCOG lists confusion, nystagmus and ataxia as neurological signs that could indicate Wernicke's encephalopathy, caused by thiamine (vitamin B1) deficiency from prolonged vomiting.

If you are struggling to cope, say so. Tommy's is explicit that severe sickness can cause anxiety, depression and suicidal thoughts, and lists the Samaritans (116 123) and the Shout crisis text line (text 85258) alongside medical help. That is not an aside — it is part of the condition.

Get support that knows this condition. Pregnancy Sickness Support (pregnancysicknesssupport.org.uk) runs a helpline on 0800 055 4361, peer support from volunteers who have been through it, and counselling. Its position on the treatment threshold is worth carrying into an appointment: "weight loss and the need for IV fluid therapy should not be a requirement for either diagnosis of HG or to get treatment."

Why this page leads with the call

Because the gap between what is possible and what people are offered is unusually wide, and because the name of the milder condition actively works against you. RCOG's guideline says the lay term "morning sickness" is "not only inaccurate (as symptoms occur both before and after noon), but is felt by sufferers to trivialise the condition."

The scale: nausea and vomiting of pregnancy affects up to 90% of pregnant women and is "one of the most common indications for hospital admission among pregnant women", while hyperemesis gravidarum affects between 0.3% and 3.6%. The NHS and HSE both put HG at 1 to 3 in every 100 pregnancies. The RCOG's patient information notes that 1 in 5 affected women may need admission to hospital for treatment.

And the biology has moved on. RCOG's guideline reports that the major mechanism relates to hypersensitivity to "the vomiting hormone growth differentiation factor-15 (GDF15)", and that hCG — the hormone usually blamed — "is therefore unlikely to be causative". This is not a psychological condition and not something you brought on yourself.

What separates HG from ordinary pregnancy sickness

RCOG uses the international Windsor definition: nausea and vomiting, of which at least one is severe, beginning in early pregnancy (before 16 weeks), an inability to eat and drink normally, and symptoms that strongly limit daily activities. Signs of dehydration contribute to the diagnosis.

Read that again, because of what is not in it. The definition deliberately shifted "from a historic reliance on objective measures such as weight loss and electrolyte imbalance, and towards subjective patient focused criteria which may lead to improved recognition and diagnosis of HG". You do not have to have lost weight to qualify.

For contrast, ordinary NVP "typically starts between the fourth and seventh weeks of gestation, peaks in approximately the ninth week and resolves by the 20th week in 90% of women". Tommy's notes HG symptoms often peak between 9 and 13 weeks, and lists the fuller picture: severe nausea, frequent vomiting, weight loss, dehydration, low blood pressure, an altered sense of smell and excess saliva. The HSE describes HG as "much worse than regular morning sickness".

One thing to stop worrying about

Ketones. RCOG's guideline states as a Grade A recommendation: "Ketonuria is not an indicator of dehydration and should not be used to assess severity." Assessing urinary ketones "does not have a use in the management of NVP or HG and may be misleading". If you have been sent home because your urine was clear of ketones, that is not a valid reason.

What is used instead: validated scores such as PUQE (Pregnancy-Unique Quantification of Emesis) and HELP (HyperEmesis Level Prediction), which RCOG says can be used to classify severity and track response to treatment.

The ginger problem

Ginger is the first thing almost everyone is told to try, and for mild to moderate sickness NICE does still say that for women "who prefer a non-pharmacological option, suggest that they try ginger".

For hyperemesis, RCOG's 2024 guideline says something quite different, and it deserves quoting at length: "There are no trials of community use of ginger for severe NVP and HG. A large cross-sectional survey of 512 women with HG found that ginger foodstuffs or over the counter tablets have little or no efficacy but caused unpleasant adverse effects and worsening of symptoms in over half (54%) of participants. Recommendations by a healthcare professional (HCP) to try ginger was found to cause a loss of trust in the HCP and damaged clinician-patient relationships. Because prior awareness and self-administration of ginger as a home remedy prior to seeking medical help was extremely high HCPs should not suggest it and doing so may delay access to effective treatment."

That last clause is the point. Ginger and dry crackers are not a treatment plan for HG, and being offered them instead of medication is a reason to ask again.

What actually helps

Antiemetics, starting early

RCOG grades this A: there are safety and efficacy data for first-line antiemetics "such as anti (H1) histamines, phenothiazines and doxylamine/pyridoxine (Xonvea)" and "they should be prescribed initially when required for NVP and HG". On second-line treatment it is equally direct: "There is evidence that ondansetron is safe and effective. Its use as a second line antiemetic should not be discouraged if first line antiemetics are ineffective." Combinations of drugs should be used when one is not enough.

The RCOG's patient information adds that Xonvea is the only licensed treatment for pregnancy sickness in the UK, and lists cyclizine, prochlorperazine, promethazine, metoclopramide, domperidone and ondansetron among the other options.

Fluids without a hospital bed

Between community care and admission sits ambulatory day care: intravenous fluids, vitamins and parenteral antiemetics given in a day unit. RCOG says this "should be used when community/primary care measures have failed". NICE's antenatal guideline agrees, advising intravenous fluids "ideally on an outpatient basis" for moderate to severe sickness, with inpatient care considered if vomiting is severe and not responding.

The things that get forgotten in an admission

• Thiamine. RCOG: thiamine supplementation "should be given to all women admitted with vomiting, or severely reduced dietary intake, especially before administration of dextrose or parenteral nutrition."
• Clot prevention. Women admitted with HG "should be offered thromboprophylaxis with low-molecular-weight heparin", because HG carries an increased risk of venous thromboembolism (odds ratio 2.5, 95% CI 2 to 3.2).
• Constipation and reflux. RCOG says women should be offered laxatives if constipated, particularly if ondansetron is used, and proton pump inhibitors for reflux.

Steroids are not an early option: RCOG says corticosteroids "should not be used until conventional treatment with intravenous fluid replacement and regular antiemetics has been proven to be ineffective".

And one line that says a great deal about how severe this condition can become: "All therapeutic measures should have been tried before considering termination of pregnancy."

The short version

If you cannot keep fluids down, are vomiting repeatedly, or your urine has stopped, that is a call today. Ask for an antiemetic by name, ask about the ambulatory day unit if tablets will not stay down, and get Pregnancy Sickness Support alongside you if you are being brushed off.