Quick answer
Hashish is a cannabis concentrate. It contains THC, the compound with anti-nausea effects. Two FDA-approved drugs use THC to treat chemotherapy-induced nausea and vomiting. Hashish itself is not a medicine. No regulator sets its THC dose. Smoking or eating hashish gives no controlled dose. Evidence for raw hashish as a nausea treatment is thin.
What the evidence covers
Two prescription cannabinoids are FDA approved in the US: dronabinol (Marinol, Syndros) and nabilone (Cesamet). Both are purified or synthetic THC. Both are labeled for nausea and vomiting from cancer chemotherapy when other drugs fail.
marijuana for vomiting reduction
Trials of smoked or inhaled cannabis for nausea are small. A 2015 systematic review found moderate-quality evidence for cannabinoids in chemotherapy-induced nausea and vomiting. Evidence for appetite and weight gain in HIV patients was low.
marijuana for vomiting reduction
What hashish is
Hashish is pressed resin from cannabis flowers. THC content ranges from about 20% to 65%, higher than most flower. A single batch can vary. That variance makes self-dosing hard. Nausea relief tracks blood THC level. A large dose can worsen nausea, raise heart rate, and cause anxiety.
Risks
Cannabinoid hyperemesis syndrome causes severe cyclic vomiting in long-term users. It is a paradox: cannabis can treat nausea and also cause it. Other risks include impaired driving, memory problems, bronchitis from smoking, and cannabis use disorder. THC passes to a fetus. People who are pregnant should not use it.
CBD and nausea
CBD is a different compound. The FDA has not approved CBD for nausea or vomiting. Most human evidence for nausea is on THC, not CBD. CBD can change how the body breaks down THC. A CBD product is not a substitute for a prescription antiemetic.
Legal status in the US
Hashish is a Schedule I controlled substance under federal law. It is illegal to buy, sell, or carry across state lines. Some states allow cannabis for medical use, including nausea. State law does not change federal law.
Talk to a clinician
Nausea has many causes: infection, migraine, pregnancy, medication, gastroparesis. A clinician can find the cause and prescribe antiemetics with known dosing, such as ondansetron, metoclopramide, or dronabinol. Ask before adding hashish to a regimen.