Urgent Care · Common Complaints
Nausea, Vomiting, and Dehydration
Most nausea and vomiting in urgent care is viral gastroenteritis. The job is to spot the surgical, metabolic, or intracranial causes — and to decide whether the patient can hydrate at home. This page covers the can't-miss diagnoses (bowel obstruction, appendicitis, DKA/HHS, increased intracranial pressure from mass or hemorrhage, MI presenting as nausea — especially older women and diabetics, pregnancy and ectopic, adrenal crisis, severe hyponatremia), red flags including bilious or feculent vomiting, persistent obstipation, the minimum safe first-pass workup (focused history, vitals including orthostatics, abdominal exam, urine pregnancy, glucose, BMP when indicated, lipase, lactate when available), antiemetic ladder, in-office IV fluids vs PO challenge, escalation criteria, documentation, and clear return precautions. Written for NPs, PAs, and MDs in outpatient practice.
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Urgent Care · Common Complaints
Nausea, Vomiting, and Dehydration
Why this symptom matters
Most cases are viral gastroenteritis. The job is to spot the surgical, metabolic, or intracranial causes — and to decide whether the patient can hydrate at home.
What must I not miss first?
- Bowel obstruction
- Appendicitis
- DKA / HHS
- Increased intracranial pressure (mass, hemorrhage)
- MI presenting as nausea (especially older women, diabetics)
- Pregnancy / ectopic
- Adrenal crisis
- Severe hyponatremia
Red flags — escalate or work up urgently
- Bilious or feculent vomiting; no flatus or BM
- Severe abdominal pain or peritoneal signs
- Hematemesis or coffee-ground emesis
- Severe dehydration: HR > 120, SBP < 90, AMS, no urine output
- Headache with vomiting, neuro deficit, or papilledema
- Diabetic with vomiting + hyperglycemia (DKA)
- Pregnancy with hyperemesis or vaginal bleeding
Immediate Management — While You Work It Up
- Ondansetron 4 mg ODT or IV — first-line antiemetic. Safe across most patients.
- IV fluids — NS or LR 1 L bolus if moderate to severe dehydration. Reassess after first liter.
- Fingerstick glucose — hypoglycemia and DKA both present with nausea and vomiting.
- Promethazine — use with caution in older adults due to sedation, fall risk, and extrapyramidal effects. Avoid if possible in adults 65 and older.
- NPO — if surgical cause has not been excluded or patient cannot tolerate oral fluids.
- Reassess vital signs after fluid resuscitation — tachycardia that does not resolve with fluids warrants escalation.
Minimum safe first-pass workup
- What to ask: duration, content (bilious, bloody, feculent), associated pain, last BM/flatus, fever, sick contacts, last meal, medications, pregnancy, head injury
- What to examine: vitals + orthostatics, abdominal exam, neuro exam, mucous membranes, skin turgor
- POC glucose, urine pregnancy test, UA
- BMP if available — esp. if diabetic, on diuretics, or appears dehydrated
- Trial PO challenge after antiemetic in clinic
What can usually be managed outpatient
- Viral gastroenteritis tolerating PO after antiemetic, vitals stable
- Migraine-associated vomiting with classic pattern, broken by treatment
- Pregnancy-related nausea, well-appearing, normal vitals, no signs of hyperemesis
- Medication-induced nausea with clear culprit and a plan to stop or change
When to escalate to ED / higher level of care
- Suspected obstruction, surgical abdomen, or perforation
- DKA, HHS, severe hyperglycemia, or significant electrolyte derangement
- Persistent vomiting unable to tolerate PO after IV/IM antiemetic and trial
- Signs of severe dehydration not correcting in clinic
- Vomiting + headache, neuro signs, or recent head injury
- Suspected MI in older adult or diabetic with isolated nausea
What to document when the diagnosis is still uncertain
- Vomiting frequency, content, duration; PO tolerance pre- and post-treatment
- Hydration status, vitals trend, glucose, pregnancy test
- "Obstruction / DKA / surgical abdomen / ICP / MI / pregnancy considered because… ruled out because…"
- Antiemetic given, response, discharge vitals, return precautions
Safety-net & return precautions to give
- Return or call 911 for blood in vomit, severe abdominal pain, no urine in 12+ hours, severe weakness or fainting, severe headache with vomiting, or chest pain.
- Sip clear fluids slowly — 1–2 oz every 10 min. If unable to keep liquids down for > 12 hours, return.
- Follow up with PCP in 24–48 hours if not improving.
Geriatric-specific modifiers (apply on top of the above)
The guidance above applies to all adult patients seen in this setting. Layer the points below for adults 55+, geriatric (65+), and frail younger adults — they are additions, not replacements.
In adults 55+, geriatric (65+), and frail younger adults, nausea and vomiting can quickly cause dehydration, AKI, electrolyte derangement, falls, and delirium. Older adults frequently present with weakness, dizziness, anorexia, or confusion rather than reporting nausea directly.
- Have a low threshold to check BMP — even brief vomiting can precipitate hyponatremia, hypokalemia, and pre-renal AKI.
- Consider atypical MI in any older adult or diabetic with isolated nausea — get an ECG before a GI diagnosis.
- Review for medication culprits using AGS Beers Criteria: opioids, GLP-1 agonists, digoxin (consider toxicity), SSRIs, antibiotics, metformin, chemotherapy.
- Hold metformin, SGLT2 inhibitors, ACEi/ARBs, and diuretics during acute illness; recheck BMP within 48 hours of resuming.
- Avoid promethazine and prochlorperazine when possible — Beers high-risk for sedation, falls, EPS, and QT prolongation. Ondansetron is preferred (check QT in patients on QT-prolonging meds).
- Always screen for occult infection (UTI, pneumonia) and intracranial process (stroke, increased ICP, subdural) — these often present in older adults as isolated nausea or AMS.
Educational guidance for clinicians. Not a substitute for clinical judgment. Always individualize to the patient and your local resources.
Evidence sources
- · ACG Nausea/Vomiting Guidelines
- · ESPEN Hydration Guidelines
Review status
Last reviewed: 2026-04
Reviewed by the MyClinicianGuide editorial team. Cadence: annual.
Educational reference for licensed clinicians (NP, PA, MD, DO). Not a substitute for clinical judgment, institutional protocols, or specialty consultation. Apply in context of the full clinical picture, patient goals, and current standards of care. See About AI guidance for AI-related limitations.
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