QUICK STEP-UP

General nausea: Zofran
Gastroparesis / stasis: Reglan
Migraine / nonspecific: Compazine
Motion / vestibular: Meclizine / Scopolamine
Anxiety / anticipatory: Lorazepam
Refractory / metabolic / palliative: Haloperidol
Chemo prophylaxis: Zofran + Dex + NK1 agent

1️⃣ FIRST-LINE COMMON OPTIONS

Ondansetron (Zofran) IV / PO / ODT

4–8 mg q6–8 PRN
15–30 min IV | 4–8 hr
Use: general nausea, post-op, chemo, medication-related
Avoid: QT prolongation, constipation, headache

✅ Most common inpatient first-line

Granisetron / Palonosetron

Longer-acting 5-HT3 antagonists
Use: chemo, post-op, refractory nausea
Avoid: constipation, QT (less with palonosetron)

Metoclopramide (Reglan) IV / PO

5–10 mg q6 PRN
15–30 min IV | 1–2 hr onset PO | 4–6 hr
Use: gastroparesis, reflux, opioid stasis, post-op nausea
Avoid: bowel obstruction, Parkinson disease, EPS, akathisia, diarrhea, QT caution

✅ Best if delayed gastric emptying

2️⃣ DOPAMINE BLOCKERS

Prochlorperazine (Compazine) IV / PO / PR

5–10 mg q6 PRN
30 min | 4–6 hr
Use: nonspecific nausea, migraine nausea
Avoid: sedation, EPS, hypotension, QT

Promethazine (Phenergan) PO / IV / IM / PR

12.5–25 mg q4–6 PRN
20 min | 4–6 hr
Use: nausea with anxiety, motion sickness, sedating bedtime option
Avoid: sedation, hypotension, delirium, tissue injury if IV extravasation

⚠️ Use PO/IM preferred over IV when possible

Haloperidol IV / PO / IM

0.5–1 mg elderly | 1–2 mg q6 PRN
15–30 min IV | 4–8 hr
Use: refractory nausea, uremic, medication-induced, palliative, metabolic nausea
Avoid: QT prolongation, Parkinson disease, EPS

✅ Strong inpatient rescue option

Chlorpromazine

10–25 mg q6 PRN
Use: refractory nausea, hiccups, palliative
Avoid: hypotension, sedation, anticholinergic effects

3️⃣ VESTIBULAR / MOTION OPTIONS

Diphenhydramine (Benadryl)

25–50 mg q6 PRN
15–30 min | 4–6 hr
Use: motion sickness, migraine adjunct, EPS treatment
Avoid: sedation, delirium, urinary retention

Meclizine

25–50 mg q8–12 PRN
1 hr | 8–24 hr
Use: vertigo, vestibular nausea, motion sickness
Avoid: sedation, anticholinergic burden

Scopolamine Patch

1 patch q72 hr
Hours onset
Use: motion sickness, vestibular nausea
Avoid: dry mouth, blurry vision, confusion (elderly), urinary retention

4️⃣ ADJUNCTS / SPECIALTY

Dexamethasone IV / PO

4–10 mg daily or peri-chemo
1 hr | long
Use: chemo nausea, refractory nausea, brain mets / ICP-related nausea
Avoid: hyperglycemia, insomnia, mood changes

Aprepitant (PO) / Fosaprepitant (IV)

Chemo protocol dosing
Use: highly emetogenic chemotherapy
Avoid: fatigue, hiccups, CYP3A4 interactions

Lorazepam / Alprazolam

Lorazepam 0.5–1 mg PRN
Use: anxiety-related nausea, anticipatory chemo nausea
Avoid: sedation, respiratory depression, delirium

Dronabinol

2.5–5 mg BID
Use: refractory nausea, chemo-related
Avoid: drowsiness, dysphoria, hypotension

🔴 BEST BY SCENARIO

General inpatient nausea

➡️ Ondansetron

Post-op nausea

➡️ Ondansetron ± Dexamethasone

Gastroparesis / opioid stasis

➡️ Metoclopramide

Migraine nausea

➡️ Compazine ± Benadryl

Motion / vertigo

➡️ Meclizine / Scopolamine

Uremic / chemical / medication nausea

➡️ Haloperidol

Palliative multifactorial nausea

➡️ Haloperidol / Chlorpromazine

Anxiety-triggered nausea

➡️ Lorazepam

🟣 HOW TO STACK TOGETHER (Different Classes Only)

Mild / General

Zofran → if partial add Compazine

Post-op

Zofran + Dex

Gastroparesis / Opioid Stasis

Reglan → if partial add Zofran

Migraine

Compazine + Benadryl

Vestibular

Meclizine or Scopolamine
(can add Zofran if mixed cause)

Uremic / Metabolic / Drug-Induced

Haloperidol → add Zofran

Severe Refractory

Zofran + Haloperidol
or
Zofran + Reglan (if stasis)

Chemo High Risk

Zofran + Dex + Aprepitant

⚠️ DO NOT STACK CARELESSLY

QT Risk Stack

Zofran + Haldol + Compazine + Reglan
➡️ Check ECG / K / Mg

EPS Risk Stack

Reglan + Haldol + Compazine
➡️ Akathisia/dystonia risk

Sedation Stack

Promethazine + Benadryl + Ativan + Chlorpromazine

⚠️ PRACTICAL PEARLS

Treat cause first: constipation, SBO, opioid effect, uremia, hyperCa, infection
If vomiting actively: use IV/IM/ODT route
Add different mechanism, not same class duplicate
Elderly: avoid anticholinergic overload

REAL WORLD HOSPITAL USE

Ondansetron
Metoclopramide
Prochlorperazine
Promethazine
Haloperidol
Meclizine
Scopolamine
Dexamethasone

Standard patient

Zofran → Reglan or Compazine → Haldol

Zofran 4 mg IV/PO q6h PRN
Reglan 5 mg IV q6h PRN (if stasis)
OR Compazine 5 mg IV q6h PRN
Haldol 0.5 mg IV q6h PRN refractory

QT patient

Meclizine / Ativan / Dex → cautious single-agent Zofran only if needed

Elderly delirium risk

Zofran only first, very cautious escalation

Adjuncts

Meclizine 25 mg PO PRN vertigo
Scopolamine patch
Ativan 0.5 mg PRN anxiety nausea

1️⃣ Low QT Risk / Standard Pt

Step-up:

Ondansetron 4 mg IV/PO/ODT q6h PRN
Metoclopramide 5–10 mg q6h PRN (stasis/opioids/fullness) or Prochlorperazine 5–10 mg q6h PRN
Haloperidol 0.5–1 mg q6h PRN refractory

Stacks:

General: Zofran → Compazine
Gastroparesis/opioids: Reglan → Zofran
Migraine: Compazine + Diphenhydramine
Refractory: Zofran + Haldol

2️⃣ QT Prolonged / QT Risk

Avoid stacking: Zofran + Haldol + Compazine + Reglan

Safer options:

Lorazepam 0.25–0.5 mg PRN
Meclizine 25 mg PRN
Scopolamine q72h
Dexamethasone 4 mg IV/PO

If needed: single low-dose Zofran only + K>4 / Mg>2 + ECG

3️⃣ Sedation-Sensitive

(elderly, delirium, OSA, weak lungs)

Use:

Zofran
Reglan (watch EPS)
Low-dose Haldol (if no Parkinson/LBD)

Avoid:
Promethazine, Diphenhydramine, Lorazepam, Chlorpromazine

4️⃣ Parkinson / Lewy Body Dementia

Avoid dopamine blockers:
❌ Haldol
❌ Compazine
❌ Reglan
❌ Promethazine