Cannabinoid Hyperemesis Syndrome - An Overview

Cannabinoid Hyperemesis Syndrome (CHS): Symptoms, Treatment and Testing

Cannabinoid hyperemesis syndrome (CHS) is a condition that causes repeated episodes of severe nausea, vomiting and stomach pain in some long-term cannabis users. It is sometimes called "scromiting", a mix of "screaming" and "vomiting", because the episodes can be so painful and distressing.

CHS can seem unlikely because cannabis is often associated with easing sickness. Many people use it for years without problems, and some use more when they feel sick, not realising it may be part of the cause. In this guide, we explain the symptoms, how CHS is diagnosed and treated, and what a cannabis drug test can and cannot tell you.

What is cannabinoid hyperemesis syndrome?

"Hyperemesis" means severe, persistent vomiting. CHS is a form of cyclic vomiting linked to prolonged cannabis use, and it was first described in medical literature in 2004.

The main active ingredient in cannabis, THC, can reduce nausea at lower doses. With repeated, high-dose use over a long period, it seems to have the opposite effect on the digestive system. Researchers do not yet know exactly why this happens, or why only some long-term users develop CHS. Theories include changes to cannabinoid receptors in the gut and brain, a build-up of cannabinoids in the body, and effects on the part of the brain that controls temperature and digestion.

How common is CHS in the UK?

University Hospital Southampton describes CHS as rare, and the true UK figure is not known. The Royal College of Emergency Medicine (RCEM) says more research is needed to establish how common it is here.

Exposure is not unusual, though. RCEM reports that 7.8% of UK adults aged 16 to 59 use cannabis, and that around a quarter of those users do so at least weekly. Reported cases are rising abroad: one US study found that emergency department visits for CHS rose from around 4 to 22 per 100,000 visits between 2016 and 2022. It is not clear how much of this is down to more cases and how much to better recognition.

Symptoms of cannabinoid hyperemesis syndrome

Symptoms are usually described in three phases.

1. Prodromal phase

This early phase can last for weeks, months or years. Symptoms may include morning nausea, stomach pain and a fear of vomiting. Most people keep eating normally, and some carry on using cannabis because they think it helps.

2. Hyperemetic phase

This is when most people seek medical help. Symptoms may include:

• Ongoing nausea and repeated, intense vomiting
• Stomach pain
• Eating less and losing weight
• Dehydration
• Taking long or frequent hot showers or baths to ease the symptoms

3. Recovery phase

Recovery begins once cannabis use stops. Symptoms ease and normal eating returns, although this can take days or months. If cannabis is used again, symptoms are likely to return.

Why do hot showers help?

Relief from hot showers or baths is one of the best-known features of CHS, and RCEM notes that patients often report it. The exact reason is unclear, but one theory is that heat counteracts the effect of cannabinoids on the body's temperature control. The relief is only temporary, and it does not treat the cause. Very hot water can also cause burns, and long hot showers can be risky for someone who is already dehydrated and may feel faint.

Who is at risk?

The main risk factor is regular, long-term cannabis use. In research cited by RCEM, 97.4% of people diagnosed with CHS used cannabis at least weekly, and 74.8% had used it regularly for more than a year. All were under 50 at the time of evaluation.

Duration varies a lot. RCEM notes that the syndrome can develop after less than one year of use or after more than 11 years. Synthetic cannabinoids have also been linked to CHS. Medical cannabis users are not automatically protected, but anyone with a prescription should speak to their prescriber before making any changes.

How is CHS diagnosed?

No blood test or scan can diagnose CHS. Doctors rely on the person's symptoms and history of cannabis use, and will first rule out other causes of vomiting, such as infection or other abdominal or neurological problems. Under the Rome IV criteria, a definite diagnosis requires vomiting episodes to stop after sustained abstinence, so it is rarely confirmed during a single hospital visit.

Diagnosis can take time. RCEM reports an average of 4.1 years from onset to diagnosis. People may be reluctant to mention cannabis, and it can be hard to spot the link when weeks or months pass between episodes. RCEM advises clinicians to reassure patients that telling them about cannabis use will remain confidential and will not count against them.

CHS or cyclic vomiting syndrome?

CHS is most often confused with cyclic vomiting syndrome (CVS), which looks very similar. Stress or infection can trigger CVS, and it is not caused by cannabis, although many people with CVS use it. In pregnancy, CHS may be mistaken for hyperemesis gravidarum, so an honest history is important.

How is CHS treated?

Hospital treatment focuses on managing symptoms and any complications. It may include:

• Intravenous fluids to treat dehydration
• Anti-sickness medicines, although standard options often do not work well for CHS
• Haloperidol or capsaicin cream, which RCEM says clinicians should consider if standard treatment fails
• Access to a hot shower or bath for symptom relief if the person is admitted

The only definitive long-term treatment is to stop using cannabis completely. Southampton's patient guidance is clear that cutting down will not get rid of CHS. If you stop, symptoms should not come back.

Stopping can be hard, especially after years of regular use. Your GP or local drug service can help, and talking therapies such as cognitive behavioural therapy may also be useful. FRANK offers free, confidential advice on 0300 123 6600.

Can CHS be dangerous?

Yes. Most people recover once they stop using cannabis, but severe, prolonged vomiting can cause dehydration and electrolyte imbalances. If untreated, these can lead to rare complications, including muscle spasms or weakness, seizures, kidney failure, heart rhythm problems, shock and brain swelling. RCEM states that CHS can be fatal at its most severe.

Can a drug test diagnose CHS?

No. A drug test can show that cannabis has been used, but it cannot show that cannabis is causing someone's symptoms. A positive result does not confirm CHS, and a home test is no substitute for medical assessment.

Testing can still have a place. Hospitals may use a urine screen to check for cannabinoids, and urine tests can provide useful feedback for people working towards abstinence with their support service. Results need careful interpretation, because regular users can test positive for some time after stopping. A positive test soon after quitting does not necessarily mean someone has used cannabis again.

Sample	Typical THC detection time	Best for
Urine	3 to 30 days, and sometimes longer with ultra sensitive tests	Home testing and routine workplace screening
Saliva	24 to 72 hours	Checking for more recent use
Blood	24 to 48 hours	Laboratory and clinical settings
Hair	Up to 90 days	Longer-term history, using laboratory analysis

These are estimates only. Detection depends on how much and how often cannabis was used, body composition and the cut-off level of the test. For a personalised estimate, try the free Drug Detection Time Calculator from UK Drug Testing, or read our cannabis drug testing guide.

Which cannabis drug test should I choose?

For most people, a urine test is the simplest and most reliable choice at home. Cannabis is harder to detect in saliva, and urine gives a longer detection window. Employers will usually want a wider panel, so that one test covers cannabis and other commonly misused drugs.

All rapid tests are screening tests. A non-negative result should be confirmed by a laboratory before any disciplinary or clinical decision is made.

What should employers know about CHS?

Repeated sickness absence can have many causes, so employers should never assume someone has CHS or try to diagnose it. If an employee discloses the condition, or a test result raises concerns, treat it confidentially and seek occupational health advice. Severe vomiting and dehydration may affect fitness for safety-critical work, so any risk should be assessed fairly. A clear policy should explain how testing works and what support is available. See our workplace drug testing guidance for more information.

Frequently asked questions

What does scromiting mean?

Scromiting is an informal term that combines "screaming" and "vomiting". It describes the severe vomiting and pain some people experience with CHS. It is not a medical diagnosis, and not everyone with CHS experiences it.

How long does an episode of CHS last?

Severe episodes often last 24 to 48 hours, but they can return unpredictably, with weeks or months between them, if cannabis use continues.

How long does CHS last after stopping cannabis?

It varies. Some people improve within days, but it can take weeks or months for symptoms to settle fully. Speak to your doctor if symptoms continue.

Can you use cannabis again after CHS?

Symptoms are likely to come back if you do. Cutting down will not get rid of CHS, so the medical advice is to stop completely.

Can CBD cause CHS?

This is not clear. Most research has looked at cannabis use in general, and the exact cause of CHS is still unknown. Some CBD products may also contain traces of THC. If you have or suspect CHS, ask your doctor before using any cannabis-derived product. Our guide to cannabis oil, CBD and THC explains the differences.

Will medical cannabis show on a drug test?

Yes, if it contains THC, a standard cannabis test can give a non-negative result. Read our guide on whether medical cannabis shows on a drug test.

Final thoughts

Cannabinoid hyperemesis syndrome is a serious but often overlooked cause of repeated vomiting in long-term cannabis users. Being open with a doctor about cannabis use can speed up diagnosis, and stopping completely is the only definitive long-term treatment. A drug test cannot diagnose CHS, but it can confirm whether cannabis is present and may support someone's wider plan to stop.

Not sure which test you need? Contact our team or call us on 01263 731 168.

Need more choice? Visit our specialist site, UK Drug Testing

The kits above are the ones I recommend most often for cannabis screening. If you are building a full workplace testing programme, though, you may want a wider choice. Our specialist sister site, UK Drug Testing, stocks a much larger range for employers and testing professionals.

Over there you will find:

• Cannabis drug tests, including ultra sensitive urine strips
• Dual chamber split cup urine drug tests, plus saliva drug tests from 4 to 13 panels
• Breathalysers
• Workplace drug and alcohol testing starter packs
• Laboratory confirmation tests
• Online drug test training

Not sure which test is right for your workplace? Take the quick quiz for a recommendation, or speak to the UK Drug Testing team Monday to Friday, 8.30am to 5pm, on 01263 731 168.

Sources: Royal College of Emergency Medicine best practice guideline: suspected cannabinoid hyperemesis syndrome in emergency departments; University Hospital Southampton NHS Foundation Trust: CHS patient factsheet; Sorensen et al: Cannabinoid Hyperemesis Syndrome, a systematic review (Journal of Medical Toxicology); ScienceAlert: report on the 2025 JAMA Network Open study of CHS emergency visits; Healthify: Cannabis hyperemesis syndrome; Drug Testing Kit: Cannabis drug testing.