Antiemetics

No patient weight set. Open Pediatric Weight, Age, Height, or Length Tape to enable dose calculations.

Antiemetics — general

Drug	Pediatric	Adult
() IV/PO/ODT	—	4–8 mg IV/PO/ODT q8h (max 16 mg/day; QTc caution)
() IV/IM	—	10 mg IV/IM q6h (EPS risk — give w/ )
() IV/IM/PO/PR	—	12.5–25 mg IV (dilute, slow) / IM / PO / PR q4–6h
() IV/IM/PO/PR	—	10 mg IV/IM or 25 mg PR q6h (EPS risk)
() IV/IM/PO	—	25–50 mg IV/IM/PO (for EPS prophylaxis or vestibular N/V)
Meclizine (Antivert) PO	Not routine <12 yr	25–50 mg PO q6–12h (vestibular/motion)
patch (Transderm Scōp)	Avoid <12 yr	1.5 mg patch behind ear q72h (motion, post-op)
() IV/PO	—	4–8 mg IV (chemo/post-op adjunct)
(Inapsine) IV/IM	Not routine in peds ED	0.625–1.25 mg IV q4–6h (QTc caution — get ECG)

Cannabinoid hyperemesis syndrome (CHS)

Suspect in chronic heavy cannabis users (often daily for ≥1 yr) with recurrent cyclical vomiting and compulsive hot-water bathing/showering that relieves symptoms. Conventional (, , ) are typically INEFFECTIVE. First-line ED therapy is topical capsaicin cream plus a antagonist ( or ) ± a . Definitive treatment is cannabis cessation — counsel at every visit. Rule out other causes of cyclic vomiting before anchoring on CHS.

Cannabinoid hyperemesis syndrome — best-evidence agents

Drug	Pediatric / Adolescent	Adult
Capsaicin 0.025–0.1% cream (TOPICAL — 1st line)	Apply thin layer to abdomen / back; ≥12 yr OK. Avoid mucous membranes; wash hands; warn re: burning sensation.	Apply to abdomen, lower back, and/or arms q4–6h PRN. Most effective single agent in CHS.
	Limited peds data; 0.05–0.075 mg/kg IV/IM (max 5 mg) if adolescent	0.05–0.1 mg/kg IV/IM (typical 2.5–5 mg). Superior to in CHS RCTs (HaVOC, Ruberto). Check QTc.
(Inapsine) IV/IM	Not routine	1.25–2.5 mg IV/IM q4–6h. QTc caution; ECG before/after.
() IV/IM/PO	—	1–2 mg IV/IM q4–6h PRN — adjunct for anxiety/retching
(Zyprexa) ODT/IM	Adolescent: 2.5–5 mg ODT	5–10 mg ODT or IM — emerging adjunct when unavailable
IV fluids + electrolyte repletion	20 mL/kg NS bolus, then maintenance; replace K+/Mg++	1–2 L NS or LR; replace K+, Mg++, glucose (D5NS if ketotic)
Hot shower (in-department if possible)	Symptomatic relief; pathognomonic feature	Symptomatic relief — supports diagnosis
AVOID	Opioids (worsen gastroparesis); repeat (ineffective, ↑QTc w/ haldol)	Same — counsel cannabis cessation as the only definitive cure

Haloperidol (Haldol) — dose calculator

Cannabinoid hyperemesis or refractory N/V. Check QTc; avoid if QTc >500 ms.

Weight— kg (set in toolbar)

Haloperidol — CHS (IV)(Haldol)
Cannabinoid hyperemesis (HaVOC, Ruberto RCTs)
First-line
IV (over 1–2 min)Onset 5–20 minDur 4–8 h
Dose
2.5–5 mg IV
0.05–0.1 mg/kg (typical 2.5–5 mg, max 5 mg)
Volume: 1.0 mL @ 5 mg/mL
- • Pre-treat or co-administer diphenhydramine 25–50 mg if EPS risk
- • Get baseline + post-dose ECG; avoid if QTc >500 ms
Haloperidol — CHS (IM)(Haldol)
No IV access
Alternative
IMOnset 15–30 minDur 4–8 h
Dose
2.5–5 mg IM
0.05–0.1 mg/kg (max 5 mg)
Volume: 1.0 mL @ 5 mg/mL