From the FDA Drug Label
While some degree of airway protection may be afforded due to active laryngeal-pharyngeal reflexes, vomiting and aspiration may occur with ketamine hydrochloride injection. The risk of vomiting is a potential side effect of IV ketamine administration, as it may occur along with aspiration 1.
From the Research
Intravenous (IV) ketamine does carry a risk of nausea and vomiting, occurring in approximately 7% of patients, as shown in a study published in 2009 2. To minimize this risk, prophylactic antiemetics are often administered before ketamine infusion. Common options include ondansetron 4-8mg IV, given 30 minutes before ketamine administration, or metoclopramide 10mg IV. For patients with a history of severe post-ketamine nausea, a combination approach may be used. During ketamine infusion, maintaining a calm environment with minimal stimulation can help reduce nausea, as sensory overload may exacerbate this side effect. Patients should be advised to fast for 4-6 hours before treatment to reduce vomiting risk. Ketamine-induced nausea occurs because the drug affects multiple neurotransmitter systems, including dopamine and serotonin pathways in the chemoreceptor trigger zone of the brain. Additionally, ketamine can increase intracranial pressure and stimulate the vestibular system, further contributing to nausea. Most cases of ketamine-induced nausea are self-limiting and resolve within 1-2 hours after infusion completion.
Some key points to consider when administering IV ketamine include:
- The risk of vomiting is not significantly associated with the initial dose of ketamine, but rather with high cumulative doses (>7 mg/kg) 2.
- Ondansetron may be more effective than metoclopramide in preventing postoperative vomiting, as shown in a study published in 2011 3.
- The use of ketamine as an adjunct to intravenous patient-controlled analgesia may not reduce the incidence of postoperative nausea and vomiting, but can reduce postoperative fentanyl consumption, as shown in a study published in 2013 4.
- A study published in 2020 highlights the clinical benefits of ketamine for treatment of acute pain and for sedation of patients undergoing mechanical ventilation, but does not specifically address the risk of vomiting 5.
- A study published in 2014 compares the efficacy of ondansetron and metoclopramide with placebo for adults with undifferentiated emergency department nausea and vomiting, and finds that reductions in nausea severity were similar for all three groups 6.
Overall, the risk of vomiting associated with IV ketamine can be minimized with proper patient selection, dosing, and administration of prophylactic antiemetics. The most effective strategy for minimizing this risk is to use ondansetron 4-8mg IV, given 30 minutes before ketamine administration, and to maintain a calm environment with minimal stimulation during ketamine infusion.