Pregnancy · Severe Sickness
Hyperemesis Gravidarum (HG) — Severe Pregnancy Sickness
When pregnancy sickness is more than morning sickness. Recognising HG, the antiemetic ladder, when to go to hospital, IV fluids with thiamine (Wernicke's prevention), and mental health support. RCOG Green-top 69 (2024).
Last reviewed 1 June 2026
Hyperemesis Gravidarum
IV thiamine, fluids, antiemetic ladder + VTE
Currently tolerating
Tier
Severe HG — admission
ADMIT. (1) Thiamine 100 mg IV before any dextrose. (2) IV 0.9 % NaCl + KCl 20–40 mmol/L titrated to serum K+. (3) Antiemetic step 3-4: metoclopramide or ondansetron IV; consider step 5 (methylprednisolone 16 mg IV TDS x 3 d then PO taper) if refractory at 48 h. (4) Prophylactic LMWH (e.g. enoxaparin 40 mg SC daily; weight-banded) — dehydration + reduced mobility = VTE risk. (5) PPI (e.g. omeprazole 20 mg PO/IV daily) if reflux. (6) Mental-health screen. (7) Daily weights, fluid balance. Re-feeding syndrome risk if pre-pregnancy underweight — slow advancement of nutrition with electrolyte monitoring.
Labs
FBC, U+E, LFTs, TFTs, urine ketones, calcium, magnesium, phosphate; repeat U+E q12-24h until normalised. cCTG / fetal-medicine input not routinely needed for HG alone.
Troubleshooting + common pitfalls
- Pitfall: Giving dextrose before thiamine.
Solution: ALWAYS thiamine 100 mg IV (or PO if mild) FIRST. Dextrose load on a thiamine-deficient brain precipitates Wernicke’s encephalopathy — permanent neurological injury. Hyperemesis patients on prolonged restricted intake are at high risk. - Pitfall: Treating HG without VTE prophylaxis.
Solution: HG + dehydration + reduced mobility = real VTE risk. RCOG GTG 37a indicates prophylactic LMWH for the admission + 7 days post-discharge. - Pitfall: Missing thyrotoxicosis associated with HG.
Solution: ~50 % of severe HG has biochemical hyperthyroidism (hCG-mediated). Most resolves spontaneously by 18–20 wk — do NOT routinely treat unless TSH-receptor antibody positive (Graves coexistence) or symptoms persist. TFTs at admission to characterise. - Pitfall: Refractory case — corticosteroids forgotten.
Solution: RCOG GTG 69 endorses methylprednisolone 16 mg IV TDS x 3 d then oral prednisolone 40 mg taper for refractory HG. Effect often dramatic. Avoid < 10 wk if possible (theoretical cleft palate signal in animal studies, not consistently seen in humans). - Pitfall: Ondansetron at < 10 wk without informed consent.
Solution: Huybrechts 2018 BMJ — small absolute increase in cleft palate (background 11 per 10,000 → 14 per 10,000). Counsel and document benefit/risk; many women accept given symptom severity. Reserve for step-4 if earlier agents fail. - Pitfall: Re-feeding syndrome in chronically malnourished woman.
Solution: Slow advancement of nutrition. Daily electrolytes (especially phosphate, magnesium, potassium) for the first 5–7 days of re-feeding. Replace before deficiency develops; dietitian input. - Pitfall: Discharging on a single antiemetic that wasn’t controlling symptoms in hospital.
Solution: Discharge meds = the regimen that achieved tolerance + at least a 12-hour observation off IV fluids. Cyclizine + ondansetron combinations are common. - Pitfall: No mental-health screen.
Solution: Severe HG is associated with depression, anxiety, PTSD, and termination considerations — offer EPDS/GAD-7 screening at admission and 2-week post-discharge. - Pitfall: Treating HG as “normal pregnancy sickness”.
Solution: Recognise diagnostic criteria (> 5 % weight loss, dehydration, electrolyte imbalance OR PUQE-24 ≥ 13). Validate the patient’s experience; HG carries real morbidity. - Pitfall: Forgetting to investigate alternative causes.
Solution: Persistent vomiting at > 20 wk, new symptoms (abdominal pain, fever, jaundice), or refractory to standard treatment → rule out cholecystitis, hepatitis, pancreatitis, UTI, surgical causes. HG typically settles by 16–20 wk; persisting suggests another aetiology. - Pitfall: Reflux symptoms not addressed.
Solution: PPI (omeprazole 20 mg) is compatible with pregnancy and improves antiemetic response when reflux is contributing. - Pitfall: Discharge without follow-up.
Solution: Day-unit review at 48 h post-discharge OR home midwife review. Up to 30 % readmission rate within 2 weeks if no structured follow-up. - Pitfall: Liver enzymes elevated — assumed HG.
Solution: ~50 % of severe HG has mildly elevated transaminases (typically < 200 IU/L), settles with hydration. But marked elevation (> 500), jaundice, RUQ pain, or PE features — rule out HELLP, AFLP, hepatitis, cholestasis.
Educational tool only — not medical advice. RCOG GTG 69; ACOG PB 189; SMFM Consult #67. Decisions and dosing by obstetric / day-unit team.
What does this mean?
Hyperemesis gravidarum (HG) is not just bad morning sickness. The diagnosis — persistent vomiting + > 5 % weight loss + dehydration + electrolyte imbalance, or PUQE-24 score ≥ 13 — affects 0.3–2 % of pregnancies and accounts for the most common non-obstetric cause of admission in pregnancy. The single most important practical rule is thiamine before dextrose — giving glucose-containing fluids to a thiamine-deficient woman precipitates Wernicke’s encephalopathy, a permanent neurological injury that is entirely preventable with a 100 mg dose given first. The antiemetic ladder runs from pyridoxine + doxylamine (step 1, outpatient) through cyclizine / promethazine / metoclopramide / ondansetron (steps 2–4) to corticosteroids (step 5, methylprednisolone IV taper) for refractory cases. Two specific risks need active management: VTE prophylaxis (HG + dehydration + immobility = real thrombosis risk; RCOG GTG 37a indicates prophylactic LMWH) and mental-health screening (HG carries elevated depression, anxiety, PTSD, and termination considerations — the suffering is real and frequently underestimated). The biochemical hyperthyroidism seen in ~50 % of severe HG is hCG-mediated and resolves by 18–20 wk without treatment unless TRAb-positive Graves coexists.
Is this hyperemesis or morning sickness?
- Morning sickness (NVP): ~80% of pregnancies. Mild. Settles by 16-20 weeks. Can drink, eat, function.
- Hyperemesis gravidarum (HG): severe. Relentless vomiting. Can’t keep fluids down. Weight loss >5%. Dehydration. Electrolyte imbalance.
PUQE score ≥13 = severe. Affects ~0.3-2% of pregnancies.
Think spectrum, not switch. Severe NVP near HG also deserves treatment — don’t wait until “official” HG.
When to seek help
Go to GP / out-of-hours / hospital if:
- Can’t keep fluids down >24 hours.
- Weight loss (clothes loose).
- Urine dark / scanty / smelly.
- Dizzy / faint / heart racing.
- No improvement despite first-line meds.
Emergency (999 / A&E): severe dehydration with confusion; chest pain; severe abdominal pain.
Antiemetic ladder (RCOG Green-top 69)
- Step 1: Vitamin B6 (pyridoxine) 10-25 mg TDS ± doxylamine 12.5 mg (combination = Xonvea / Diclectin).
- Step 2: Cyclizine 50 mg or promethazine 12.5-25 mg TDS.
- Step 3: Metoclopramide 10 mg TDS (max 5 days) OR prochlorperazine.
- Step 4: Ondansetron 4-8 mg (caution before 10 weeks — slight cleft palate signal in some studies; benefits often outweigh risks).
- Step 5: Corticosteroids (methylprednisolone IV then oral prednisolone taper).
Climb ladder until controlled. None cause major fetal harm at standard doses.
Thiamine before dextrose — why
Severe HG patients are depleted in vitamin B1 (thiamine). Giving glucose-containing fluids BEFORE thiamine can precipitate Wernicke’s encephalopathy — confusion, ataxia, eye movement problems. Can become permanent (Korsakoff’s syndrome).
Protocol: 100 mg IV thiamine first (or oral 50 mg if mild), THEN any dextrose-containing fluids.
Can HG hurt my baby?
Usually NO direct harm to baby if managed properly.
Potential risks if severe / untreated:
- Mild low birth weight (often catches up after birth).
- Preterm birth (slight increase).
- Maternal malnutrition / electrolyte issues briefly affecting baby.
Critical: getting fluids + electrolytes + antiemetics keeps both safe. Worry MORE about untreated severe HG than about meds.
Will HG come back next pregnancy?
~75-85% recurrence rate. If you had it last pregnancy, chance is high again.
Planning next pregnancy:
- Start antiemetics from positive test (don’t wait for vomiting).
- Book early with GP / midwife.
- Plan time off work.
- Arrange support (childcare for existing children, household help).
- Mental health support — HG is traumatic; PTSD common.
Sister / mother history of HG raises your risk. Possible genetic component (GDF15 gene).
Different scenarios — HG
Scenario 1: 8 weeks, vomiting 6x/day, can’t keep fluids down
GP: prescribe cyclizine + ondansetron. If not improving in 24-48h, ambulatory day unit for IV fluids + thiamine. Consider time off work.
Scenario 2: HG diagnosed, second baby, severe
Recurrence high. Plan: childcare for existing child; partner / family support; HG clinic referral; consider preconception antiemetics next time.
Scenario 3: 18 weeks, HG still severe, lost 10% weight
Specialist referral. Escalate antiemetics including steroids. Possible TPN (total parenteral nutrition) via central line. Mental health support critical.
Scenario 4: HG resolved at 20 weeks, traumatised by experience
Perinatal mental health referral. Counselling. PSS (Pregnancy Sickness Support) peer support. Plan for postnatal mental health check-ins.
Scenario 5: HG + considering termination due to severity
Valid feelings. Specialist counselling. Mental health support without judgement. Some women choose termination — respected. Others manage with full treatment and reach end of pregnancy. Personal decision with care team.
Care guidance — surviving HG
- Don’t “push through” — get help early.
- Antiemetics are safe; use them.
- IV fluids when oral fails.
- Thiamine before dextrose.
- Calories + hydration > balanced diet.
- Eat whatever stays down — even just toast / crackers / lollies.
- Avoid strong smells.
- Time off work via fit note.
- Reject invalidating comments — HG is NOT just morning sickness.
- Mental health support — ~50% develop depression / anxiety.
- PSS (Pregnancy Sickness Support) — UK charity with helpline + peers.
- Domestic help — accept it.
- Postnatal debrief if traumatic.
Sources
- RCOG Green-top Guideline 69 (2024). The management of nausea and vomiting of pregnancy and hyperemesis gravidarum.
- NICE CG62. Antenatal care for uncomplicated pregnancies.
- Pregnancy Sickness Support (UK charity). www.pregnancysicknesssupport.org.uk
- Fejzo MS, et al. Nausea and vomiting of pregnancy and hyperemesis gravidarum. Nat Rev Dis Primers 2019.
- Madjunkov M, et al. Hyperemesis gravidarum: review of pathogenesis and treatment. J Obstet Gynaecol Can.
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Frequently asked questions
Is my morning sickness severe enough to be hyperemesis?
MORNING SICKNESS (nausea + vomiting of pregnancy, NVP) affects ~80% — typically mild, settles by 16-20 weeks, you can still drink + eat + function. HYPEREMESIS GRAVIDARUM (HG) is SEVERE — relentless vomiting, can't keep fluids down, weight loss (>5% body weight), dehydration, electrolyte imbalance, struggle to function. PUQE SCORE: tool to assess severity. PUQE ≥ 13 = severe. AFFECTS ~0.3-2% of pregnancies. THINK SPECTRUM not switch. Severe NVP near HG also deserves treatment — don't wait until 'official' HG to ask for help. SEE GP / midwife / hospital if not keeping fluids down >24 hours.
When should I go to hospital for sickness?
GO TO GP / OUT-OF-HOURS / HOSPITAL if: (1) CAN'T KEEP fluids down >24 hours; (2) WEIGHT LOSS (clothes loose); (3) URINE DARK / scanty / smelly (dehydration); (4) DIZZY / faint / heart racing; (5) NO IMPROVEMENT despite first-line meds. EMERGENCY (999 / A&E) if: severe dehydration with confusion; chest pain; severe abdominal pain. NHS pathway: GP can prescribe orally; if not working, day-case ambulatory unit for IV fluids + antiemetics (avoid full admission); only admit if severe. NEVER 'just push through' — HG can have lasting health impact.
What medications are safe to treat severe sickness?
MEDICATION LADDER (RCOG Green-top 69 / 2024): STEP 1: VITAMIN B6 (pyridoxine) 10-25 mg three times daily ± DOXYLAMINE 12.5 mg (combination = 'Xonvea' / Diclectin). STEP 2: CYCLIZINE 50 mg or PROMETHAZINE 12.5-25 mg three times daily. STEP 3: METOCLOPRAMIDE 10 mg three times daily (caution: max 5 days due to extrapyramidal side effects) OR PROCHLORPERAZINE. STEP 4: ONDANSETRON 4-8 mg (caution before 10 weeks — slight cleft palate signal in some studies; benefits often outweigh risks). STEP 5: CORTICOSTEROIDS (methylprednisolone IV then oral prednisolone taper) — last-line. CLIMB ladder until controlled. SAFE — none cause major fetal harm at standard doses.
Can hyperemesis hurt my baby?
Usually NO direct harm to baby if managed properly. POTENTIAL RISKS if SEVERE / untreated: (1) MILD LOW BIRTH WEIGHT (often catches up after birth); (2) PRETERM BIRTH (slight increase if severe); (3) ELECTROLYTE issues in mother affecting baby briefly; (4) MATERNAL malnutrition impacts pregnancy. CRITICAL POINT: getting fluids + electrolytes + antiemetics keeps both safe. UNDIAGNOSED RISK: Wernicke's encephalopathy (B1 / thiamine deficiency) — preventable by giving THIAMINE before IV dextrose. PHARMACEUTICAL teratogen risk: minimal at standard doses for all the antiemetics in modern protocols. WORRY MORE about untreated severe HG than meds.
Why does thiamine get given first?
WERNICKE'S ENCEPHALOPATHY PREVENTION. Severe HG patients can't eat properly for weeks; depleted in vitamin B1 (thiamine). Giving GLUCOSE-containing fluids (saline + dextrose) BEFORE thiamine forces the body's glucose metabolism without the cofactor needed (thiamine) — depletes CNS thiamine acutely and PRECIPITATES Wernicke's: confusion, ataxia, eye movement problems. Can become PERMANENT (Korsakoff's syndrome — chronic memory loss). PROTOCOL: 100 mg IV thiamine first (or oral 50 mg if mild), THEN any dextrose-containing fluids. THIS IS STANDARD UK hospital practice for severe HG / suspected HG patients getting IV fluids.
Will my hyperemesis come back next pregnancy?
USUALLY YES — ~75-85% recurrence rate. IF you had it last pregnancy, chance is high you'll have it again. CAN BE: similar severity, worse, or sometimes milder. PLANNING NEXT PREGNANCY: (1) start antiemetics from POSITIVE TEST (don't wait for vomiting); (2) book early with GP / midwife / GIN specialist; (3) plan time off work; (4) arrange support (childcare for existing children, household help); (5) mental health support — HG is traumatic; PTSD common after severe HG. SISTER / MOTHER history of HG raises your risk. POSSIBLE GENETIC component (GDF15 gene). DON'T let fear prevent another pregnancy — treatment is much better now.
How does PUQE-24 score work?
PUQE-24 (Pregnancy-Unique Quantification of Emesis 24h): 3-question score, total 3-15. Q1: HOW LONG nausea per day (none / ≤1 hr / 2-3 hr / 4-6 hr / >6 hr). Q2: HOW MANY TIMES vomited last 24 hours (none / 1-2 / 3-4 / 5-6 / ≥7). Q3: HOW MANY TIMES retched without vomiting (none / 1-2 / 3-4 / 5-6 / ≥7). EACH 1-5 points → TOTAL: MILD (3-6), MODERATE (7-12), SEVERE (≥13). USE TO: (1) track progression over time; (2) communicate severity to clinicians; (3) guide treatment escalation. SOME hospitals require certain PUQE for IV fluid pathway access.
What if antiemetics aren't working?
ESCALATE through ladder. STEP UP plus combination therapy: pyridoxine + cyclizine + metoclopramide simultaneously often more effective than single drug. ADD ONDANSETRON if vomiting dominant. IV FLUIDS for dehydration even if oral meds continuing. SEEK SPECIALIST: HG clinic, day unit, EPAU (early pregnancy assessment unit). STEROIDS as last resort (methylprednisolone IV 16 mg three times daily for 3 days then oral prednisolone 40 mg taper). RARE: total parenteral nutrition (TPN) via central line for refractory cases. CONSIDER PERSONAL alarms / red flags: dehydration, ketosis, electrolyte imbalance → ESCALATE.
How long does hyperemesis last?
VARIABLE. MOST cases improve from 16-20 WEEKS as placenta hormones plateau. SOME WOMEN have HG that continues throughout pregnancy (up to birth). RANGE: 10-15% have all-pregnancy HG. RESOLUTION: dramatic after delivery — most women feel transformed within hours-days. NOT every pregnancy improves at 16-20 weeks — if persisting, continue treatment without judgment. DOCUMENT impact: weight, fluid intake, mood — to communicate severity to team. Many women describe HG as the hardest experience of their life — TAKE IT SERIOUSLY, don't apologise for asking for help.
Can I still work / function with hyperemesis?
VARIES. SOME continue working (often reduced hours / from home if possible). MANY cannot work at all — severe HG is disabling. FIT NOTE from GP for time off. UK: employer must do risk assessment; can't dismiss for pregnancy-related illness; statutory sick pay available. SUPPORT: NHS HG clinics; PRIVATE: HG specialists; CHARITY: Pregnancy Sickness Support (UK charity with helpline, peer support, doctors' database). DOMESTIC HELP IF possible — friends, family, paid cleaner / cook. ACCEPT help. RECOGNISE this is a real medical condition, not 'just morning sickness'.
Will I be able to look after my other children?
VERY DIFFICULT. HG is debilitating. STRATEGIES: (1) HONESTY with older children — 'Mummy is unwell because of the baby'; (2) HELP from partner / family / friends; (3) PAID childcare if possible; (4) NURSERY / preschool if not already; (5) BIRTHDAY simple, low-energy activities, lots of screen time / quiet play; (6) ASK partner to do school runs / bedtimes; (7) REJECT GUILT — you're surviving a severe illness. CHILDREN are resilient. Your priority is treatment / hydration / antiemetics. Visiting relatives / playdates for older children to take pressure off. Pregnancy Sickness Support has resources for HG mothers with toddlers.
What about feeding / nutrition with hyperemesis?
GOAL is fluid + calories, not 'balanced' diet. EAT WHATEVER stays down — even if it's just toast, crackers, ice lollies, sweets, chocolate. NUTRITION matters less than CALORIES + HYDRATION short-term. ICE / ice lollies often easier than water. ELECTROLYTE drinks (Dioralyte, ORS) helpful. AVOID strong smells (cooking, perfumes, fish). EAT lying down sometimes works. SMALL frequent intake better than big meals. SUPPLEMENTS: PREGNANCY VITAMINS if can keep down (or rectal forms via specialist). DON'T worry about baby getting enough — they prioritise themselves; you need calories + hydration.
What about IV fluids and ketones in urine?
KETONES in urine ≠ dehydration anymore (old marker). Modern guidance: ketones don't reliably indicate severity. USE clinical signs (HR, BP, postural drop, urine output, mucous membranes) + biochemistry (urea, creatinine, electrolytes). IV FLUIDS protocol: NORMAL SALINE (0.9% NaCl) WITH ADDED POTASSIUM — usually 40 mmol KCl per litre. RATE: 1L over 4-6 hours typically, then 1-2L over 24 hours. ADD THIAMINE 100 mg IV BEFORE dextrose-containing fluids (Wernicke's prevention). REASSESS every few hours. AMBULATORY units (day-case) often used to avoid hospital admission.
What about mental health and hyperemesis?
HUGE IMPACT. ~50% develop depression / anxiety during HG. PTSD common after severe HG (~1 in 5). NOT IMAGINED — biological + psychological + social. SUPPORT: PSS (Pregnancy Sickness Support charity helpline + peer); GP / perinatal mental health team; counselling. PARTNER also affected — watching partner suffer is hard. AVOID INVALIDATING comments ('try ginger biscuits!', 'I had morning sickness too'). HG IS NOT THE SAME as normal pregnancy sickness. SOME WOMEN consider termination due to severity; mental health support important during this. POSTNATAL: PND screening; debrief / counselling for trauma.
Anything I should NOT do?
(1) DON'T 'push through' — get help early. (2) DON'T be told 'it's just morning sickness' if it's HG. (3) DON'T accept 'ginger biscuits' as the only suggestion. (4) DON'T stop antiemetics without medical advice — most are safe long-term. (5) DON'T avoid IV fluids out of unfounded medication fear. (6) DON'T blame yourself — HG is biological. (7) DON'T isolate — PSS / peer support helps. (8) DON'T undermine your needs to be 'a strong pregnant woman'. (9) DON'T accept 'cure' suggestions from random people. (10) DON'T travel internationally during HG flare-ups.
How does this relate to other calculators on BumpBites?
Companion: /calculators/puqe-score for severity scoring; /calculators/pregnancy-symptom-check; /calculators/pregnancy-nutrition; /calculators/postpartum-depression-quiz for mental-health screening; /calculators/water-intake; /calculators/pregnancy-week for gestation timeline; /calculators/gad7-perinatal for anxiety screening.