Hyperemesis gravidarum (HG) is severe pregnancy-related nausea and vomiting that can make it hard to eat, drink, function, or get through the day. It can be physically and emotionally overwhelming, and needing medical treatment is not a failure. Treatment is led by a maternity clinician and may include anti-sickness medicine, IV fluids, thiamine, electrolyte monitoring, and hospital care when vomiting or poor intake cannot be managed safely at home.
HG is more than ordinary “morning sickness.” Current UK guidance describes it as a severe form of pregnancy nausea and vomiting that interferes with quality of life and the ability to eat or drink normally.
When Severe Vomiting in Pregnancy Needs Urgent Assessment
Contact your maternity team, obstetric clinician, or urgent care service today if vomiting is severe or persistent, or if it is preventing you from keeping fluids down. Do not wait for symptoms to become unbearable before asking for help: early treatment may help prevent more serious complications, including hospitalization.
Seek Urgent in-Person Care Now If You Have
- Inability to keep fluids down
- Markedly reduced urination
- Fainting, confusion
- Blood in your vomit
- Severe abdominal pain
- Fever
These symptoms need prompt assessment because vomiting in pregnancy is not always caused by HG. Clinicians need to distinguish pregnancy-related nausea and vomiting from other possible causes.
What Clinicians Assess
There is no single test that can confirm HG; clinicians assess the whole picture: how often you are vomiting, whether you can drink or eat, your urine output, recent weight change, and how symptoms are affecting daily life.
Older guidance described HG using prolonged nausea and vomiting with dehydration, electrolyte imbalance, and more than 5% loss of prepregnancy weight. Those findings can signal serious illness, but they are not a threshold you need to reach before seeking care.
Depending on your symptoms and examination findings, your care team may evaluate for dehydration, nutritional problems, electrolyte disturbances, and other possible causes of vomiting.
What to Track Before an Appointment
If possible, write down:
- When nausea and vomiting started
- How often you are vomiting
- What drinks, foods, or medicines you can keep down
- When you last urinated and whether output is much lower than usual
- Any recent weight change
- Medicines you have already tried and whether they helped
- Other symptoms, such as abdominal pain, fever, diarrhea, urinary symptoms, headache, or dizziness
This information can help your clinician decide how quickly treatment needs to escalate.
Anti-Sickness Medicine is Usually the First Medical Step
For HG, dietary changes alone are not enough. A clinician may prescribe an antiemetic, meaning an anti-sickness medicine, and then review whether it is controlling vomiting and allowing you to drink, eat, and function more normally. 
Treatment is individualized. One medicine may work well for one person and not another. Some people need a different medicine, a change in how it is given, or more than one antiemetic under clinical supervision.
Detailed medication sequencing varies by country, local protocols, pregnancy stage, medical history, and previous treatment response. In the 2016 RCOG guidance, cyclizine, prochlorperazine, promethazine, and chlorpromazine were listed as first-line options. Metoclopramide and ondansetron were listed as second-line options. That classification should not be treated as a personal prescription or a universal current order of treatment.
A Note on Ondansetron
Ondansetron is one antiemetic that a prescriber may consider during pregnancy when the expected benefit of treatment outweighs potential fetal risks. It is used off-label for pregnancy nausea, vomiting, and HG in the UK, so the decision remains an individual prescribing decision.
Medication concerns are understandable, especially when symptoms are severe. The practical question for your clinician is not simply whether a medicine carries any risk, but whether its expected benefits to your health, hydration, nutrition, and pregnancy outweigh those risks.
Do not start, stop, double, or combine anti-sickness medicines without advice from your maternity clinician or prescriber.
When IV Fluids, Day Care, or Hospital Admission May be Needed
If you cannot take enough fluid or medicine by mouth, care may need to move beyond home treatment. Depending on local services, this may involve ambulatory or day-care treatment, urgent assessment, or hospital admission.
In older RCOG care pathways, ambulatory care could provide IV fluids, antiemetics, and thiamine after community treatment had not worked. Inpatient care was considered when symptoms or complications could not be safely managed through ambulatory care. Current local admission decisions should be based on your full clinical picture rather than one score, urine test, or weight-loss figure.
What IV Treatment Can Address
In-person treatment may include:
- IV fluids to treat dehydration when drinking is not possible or sufficient
- Antiemetics given in a form that does not rely on keeping tablets down
- Electrolyte checks and replacement when vomiting or poor intake has disrupted the body’s fluid and mineral balance
- Thiamine, a vitamin that may be needed with prolonged vomiting and poor intake
Older guidance specifically called for thiamine for prolonged vomiting and before dextrose-containing IV treatment. This is one reason IV treatment should be clinician-directed rather than attempted through self-treatment.
People receiving IV or inpatient care may need repeat blood tests to monitor hydration and electrolytes. The exact tests, frequency, fluid choice, and discharge plan depend on the clinical setting and your results.
When Symptoms Do Not Improve
Some cases of HG remain difficult to control despite standard antiemetics and IV support. Ongoing inability to drink, eat, or manage daily activities deserves reassessment—not simply more pressure to “push through.”
In the 2016 RCOG guidance, corticosteroids were reserved for HG that had not responded to standard treatment. This is specialist-led treatment, not a routine next step or a medicine to request without assessment.
Your care team may need to reconsider the antiemetic plan, reassess hydration and nutrition, or arrange more intensive support. The goal is not just to reduce vomiting on paper, but to help restore safe fluid intake, nutrition where possible, and day-to-day functioning.
Food and Drink Strategies Have a Limited Role
For mild pregnancy nausea, lifestyle and dietary changes may help. With HG, however, they are supportive measures—not a replacement for medical treatment.
If you can tolerate anything, it may help to focus on whatever fluids or foods you can currently manage while waiting for clinical advice. But do not delay care because you are unable to follow typical nausea tips, such as eating small meals or avoiding certain foods. Severe vomiting needs medical attention.
What to Ask at Your Next Review
Use these questions to guide the conversation with your maternity team:
- Am I hydrated enough, or do I need IV fluids?
- Is my current anti-sickness medicine working well enough?
- What should I do if I cannot keep the medicine down?
- Do I need blood tests or repeat electrolyte checks?
- Has prolonged vomiting made thiamine supplementation necessary?
- What symptoms mean I should return urgently?
- When and how will my treatment plan be reviewed?
Severe or persistent vomiting in pregnancy deserves care. Contact your maternity team today if you cannot maintain fluids, your urination is much reduced, treatment is not restoring daily functioning, or you are worried about how unwell you feel. Seek urgent in-person help immediately for fainting, confusion, blood in vomit, severe abdominal pain, fever, or inability to keep fluids down.
