bubble_chart Synergistic tendency



The combination of these substances attenuates some of their effects and increases others.
Reliability: hypothetical.
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error_outline Estimated risk



This combination presents relatively low physical or mental risks, or may result in risky situations.
Reliability: hypothetical.
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flare About effects

Of the seven user reports found (1, 2, 3, 4, 5, 6, 7): three (2, 3, 4) report nausea; two (2, 3) report high anxiety; two (1, 6) report discomfort; two (5, 7) describe a more energetic and lucid experience.

In mice, small doses of ketamine increase locomotor activity (but not high doses). In this study and this one, the combination of caffeine and ketamine increased locomotor activity more than either product alone. This is consistent with some reports of more energetic experiences (5, 7).

The two products do not appear to interact kinetically.

menu_book About risks

Feedback reports cases of nausea (2, 3, 4), anxiety (2, 3) and discomfort (1, 6). The small number of feedbacks, despite the widespread use of caffeine, and their almost exclusively negative nature, perhaps indicate that users only report problems, which therefore seem to be rather rare.

Independently, both products increase blood pressure, and it is likely that such effects are added when the two are mixed, which could be an issue for people suffering from hypertension. According to this systematic review in humans, the increase in blood pressure caused by caffeine is potentiated by stress and disappears with regular intake, which leads to tolerance. In this study on humans, 0.5 mg/kg of ketamine (a dose supposed to enable consciousness) increased blood pressure only slightly.

The combination of anaesthetic and stimulant effects theoretically entails contextual risks (e.g. of injury), although we found no reports of this.

According to this study, caffeine lowers the lethal dose of ketamine in mice.