ConditionDigestive system
Persistent Vomiting of Unknown Cause
Persistent vomiting of unknown cause describes vomiting that lasts or keeps returning over weeks without an obvious explanation such as a stomach bug, pregnancy or a known illness. It is not a final diagnosis but a starting point for investigation. Common explanations found on testing include gastroparesis, cannabinoid hyperemesis syndrome, cyclic vomiting syndrome, medication side effects, functional disorders and, less often, blockages, hormonal problems or brain causes. Treatment depends on the cause, plus fluids and anti-nausea medicine.
Also called: Chronic unexplained vomiting, recurrent vomiting, chronic nausea and vomiting
At a glance
- What it is
- Vomiting lasting more than a week or recurring over weeks without a clear cause.
- Common causes found
- Gastroparesis, cannabis use, cyclic vomiting, medicines, reflux, functional disorders, pregnancy.
- Serious causes to rule out
- Bowel obstruction, ulcers, cancer, raised brain pressure, kidney or adrenal problems.
- Tests
- Blood tests, pregnancy test, endoscopy, imaging, gastric emptying study.
- Treatment
- Rehydration, anti-nausea medicines, treating the cause, dietary changes.
When to get help
Call 911 or go to the ER
- Vomiting blood or coffee-ground material, or black stools
- Green (bile) vomiting with a swollen belly and no stool or gas (possible bowel obstruction)
- Severe belly pain, chest pain, a stiff neck with fever, or confusion
- Vomiting with a severe headache, especially on waking, vision changes or weakness
- Signs of severe dehydration: no urine for 8 hours or more, dizziness on standing, fainting
See a doctor within a day or two
- Unable to keep down any fluids for 24 hours
- Vomiting with unexplained weight loss, difficulty swallowing or feeling full after small meals
- Vomiting in someone with diabetes and high blood sugar or ketones
- Vomiting in pregnancy with weight loss
Book a routine appointment
- Vomiting episodes that recur over weeks or months with well periods in between
- Daily nausea and vomiting for more than a week
- Vomiting that started after a new medicine
Common causes of persistent vomiting
| Cause | Clues |
|---|---|
| Gastroparesis | Vomiting undigested food hours after eating, fullness, bloating; often with diabetes or after surgery or viral illness |
| Cannabinoid hyperemesis syndrome | Regular cannabis use, recurrent bouts of vomiting, relief from hot showers |
| Cyclic vomiting syndrome | Stereotyped episodes of intense vomiting lasting hours to days, with well periods; often migraine history |
| Medicines | Opioids, GLP-1 medicines, chemotherapy, antibiotics, metformin, NSAIDs, iron, digoxin |
| Functional dyspepsia and chronic nausea and vomiting syndrome | Long-standing nausea and vomiting with normal tests |
| Rumination syndrome | Effortless regurgitation of food within minutes of eating, often re-chewed or spat out |
| Reflux and peptic ulcer disease | Heartburn, upper belly pain |
| Pregnancy | Morning sickness or hyperemesis gravidarum |
| Alcohol | Morning vomiting with heavy use |
Serious causes to rule out
- mechanical blockage: gastric outlet obstruction from ulcers or cancer, bowel obstruction, adhesions after surgery
- gallbladder and pancreas disease
- brain causes: raised intracranial pressure, tumors, migraine, vestibular disorders
- metabolic and hormonal: diabetic ketoacidosis, kidney failure, high calcium, Addison's disease, thyroid disease
- eating disorders with self-induced vomiting
- cancers of the stomach, pancreas or elsewhere
Questions your doctor will ask
- when vomiting happens and how soon after eating
- what the vomit looks like (undigested food, bile, blood)
- whether there are well periods between episodes
- cannabis, alcohol and medication use, including recent changes
- weight change, appetite, bowel habits, headaches, dizziness
- possibility of pregnancy
- diabetes, previous surgery and family history
Tests
- blood tests: electrolytes, kidney and liver function, glucose, calcium, lipase, thyroid, morning cortisol; pregnancy test
- upper endoscopy to look for ulcers, blockage or inflammation
- imaging: abdominal X-ray, ultrasound, CT or MR enterography
- gastric emptying scintigraphy for gastroparesis (after stopping medicines that affect emptying, including cannabis and opioids)
- brain MRI if there are neurological signs or early-morning vomiting with headache
- specialist testing such as high-resolution manometry for rumination
Treatment
Immediate care
- oral rehydration solution in small, frequent sips; IV fluids if needed
- anti-nausea medicines such as ondansetron, metoclopramide, prochlorperazine or promethazine, prescribed by a doctor
Treating the cause
- gastroparesis: small, low-fat, low-fiber meals, blood sugar control, prokinetic medicines
- cannabinoid hyperemesis: stopping cannabis completely is the only lasting cure; capsaicin cream and haloperidol can help acute episodes
- cyclic vomiting: preventive medicines such as amitriptyline or topiramate; early treatment of episodes with anti-nausea medicines, sumatriptan and rest in a dark room
- medication-induced: dose change or alternative medicine
- rumination: diaphragmatic breathing training
- functional disorders: low-dose tricyclic antidepressants or mirtazapine, and psychological therapies
Complications
- dehydration and kidney injury
- low potassium and sodium
- tears or bleeding in the esophagus (Mallory-Weiss tear)
- weight loss and malnutrition
- dental erosion
- aspiration pneumonia
Frequently asked questions
What can cause vomiting for weeks with no obvious reason?
Common causes found after testing include gastroparesis, cannabis use (cannabinoid hyperemesis syndrome), cyclic vomiting syndrome, medication side effects, reflux or ulcers, and functional nausea and vomiting disorders. Less often, blockages, hormonal problems or brain conditions are responsible.
When should I see a doctor for persistent vomiting?
See a doctor if vomiting lasts more than a few days, keeps recurring, or comes with weight loss, belly pain or difficulty swallowing. Seek emergency care for vomiting blood, green vomit with a swollen belly, severe pain, severe headache or signs of dehydration.
Can cannabis cause persistent vomiting?
Yes. Regular, long-term cannabis use can cause cannabinoid hyperemesis syndrome, with repeated bouts of severe nausea and vomiting often relieved by hot showers. Symptoms resolve only after stopping cannabis completely, which may take weeks.
What is cyclic vomiting syndrome?
It is a disorder of repeated, similar episodes of intense nausea and vomiting lasting hours to days, separated by symptom-free periods. It is linked to migraine and is treated with preventive medicines and early treatment of episodes.
Sources
This guide was written from current patient and clinical guidance, including:
- American Gastroenterological Association: Technical review on nausea and vomiting
- American Neurogastroenterology and Motility Society/Cyclic Vomiting Syndrome Association: Guidelines on cyclic vomiting syndrome
- American College of Gastroenterology: Clinical guideline: gastroparesis
- Rome Foundation: Rome IV criteria for nausea and vomiting disorders
- MedlinePlus: Nausea and vomiting