Review Article
Cardiovascular Health & Substance Use

Impact of Khat (Catha Edulis) Chewing/Use on Heart Rate and Blood Pressure: A Critical Review

Background

Khat (Catha edulis) is an evergreen flowering plant native to the Horn of Africa and the Arabian Peninsula whose fresh leaves and young shoots are widely chewed for their stimulant psychoactive effects. An estimated 20 million people worldwide use khat regularly, with the practice deeply embedded in the social and cultural traditions of communities in Ethiopia, Kenya, Somalia, Yemen, and other countries in East Africa and the Middle East. The practice has also spread to diaspora communities in Europe, North America, and Asia through international migration.

The primary psychoactive component of khat is cathinone (S-(-)-cathinone), an alkaloid that is structurally and pharmacologically similar to amphetamine. Like amphetamine, cathinone acts as a central nervous system stimulant by promoting the release of catecholamines (norepinephrine and dopamine) and inhibiting their reuptake at sympathetic nerve terminals. A second alkaloid, cathine (norpseudoephedrine), is present in older or dried leaves where cathinone has been oxidised, and produces similar but less potent sympathomimetic effects. These pharmacological properties account for khat’s subjective effects of euphoria, increased alertness, suppressed appetite, and enhanced energy, as well as its cardiovascular effects including elevated heart rate and blood pressure.

The cardiovascular implications of khat use have become a growing public health concern. Case reports and clinical studies have linked khat chewing to acute coronary syndromes, myocardial infarction, cerebrovascular events, cardiomyopathy, and heart failure. However, the precise magnitude and mechanisms of khat’s effects on fundamental cardiovascular parameters—specifically heart rate and blood pressure—have been the subject of varying findings across studies conducted in different populations, with different designs, and measuring effects at different time points relative to khat use.

Methodology of the Review

This critical review, published in the Malaysian Journal of Public Health Medicine, systematically examined the published literature on the effects of khat chewing and its active constituents on heart rate and blood pressure. The review synthesised findings from human epidemiological studies, experimental human studies, and animal research to construct a comprehensive assessment of the cardiovascular haemodynamic effects of khat.

The review evaluated both acute effects (measured during or immediately after khat chewing sessions) and chronic effects (comparing habitual khat chewers with non-chewers in cross-sectional or longitudinal designs). This distinction is important because the acute sympathomimetic response to khat may differ from the sustained cardiovascular effects of habitual use, which could involve adaptive responses, tolerance, or cumulative cardiovascular damage.

Effects on Blood Pressure

The evidence reviewed consistently indicated that khat chewing is associated with elevations in both systolic and diastolic blood pressure. The acute effect of khat on blood pressure has been demonstrated in experimental studies where blood pressure measurements were taken at intervals during and after khat chewing sessions. These studies typically show a progressive rise in blood pressure that begins within 30 to 60 minutes of commencing chewing and may persist for several hours.

Cross-sectional studies comparing habitual khat chewers with non-chewers have provided evidence for sustained blood pressure elevation beyond the acute pharmacological effect. A study among adults in Butajira, Ethiopia, found that regular khat chewers had significantly higher mean diastolic blood pressure (75.0 mmHg versus 72.9 mmHg) and higher prevalence of hypertension (13.4% versus 10.7%) compared to non-chewers. A later systematic review and meta-analysis consolidated evidence from multiple studies, finding that khat chewers had mean systolic blood pressure 7.9 mmHg higher and mean diastolic blood pressure 5.1 mmHg higher than non-chewers.

These magnitudes of blood pressure elevation, while modest at the individual level, are clinically significant at the population level. Epidemiological evidence from large cohort studies has established that even small sustained increases in blood pressure translate to meaningfully increased risks of cardiovascular events including stroke, myocardial infarction, and heart failure over time. A 5 mmHg population-wide increase in diastolic blood pressure, for example, has been estimated to increase stroke risk by approximately 35% and coronary heart disease risk by approximately 20%.

Effects on Heart Rate

The sympathomimetic action of cathinone predictably produces increases in heart rate through beta-1 adrenergic stimulation of the sinoatrial node. The review found that acute khat chewing sessions produce measurable tachycardia, typically in the range of 5 to 15 beats per minute above baseline. Meta-analytic data indicated a mean heart rate difference of 6.9 beats per minute between khat chewers and non-chewers.

Sustained tachycardia in habitual khat users may contribute to cardiovascular risk through several mechanisms. Elevated resting heart rate is an independent risk factor for cardiovascular mortality, and the chronic sympathetic activation associated with habitual khat use may predispose users to cardiac arrhythmias, increased myocardial oxygen demand, and accelerated progression of atherosclerotic disease.

Proposed Mechanisms

The cardiovascular effects of khat are primarily attributed to the sympathomimetic actions of cathinone and, to a lesser extent, cathine. Cathinone promotes the release of norepinephrine from sympathetic nerve terminals and inhibits its reuptake, producing effects analogous to those of amphetamine on the cardiovascular system. This results in increased cardiac contractility and heart rate (positive inotropic and chronotropic effects) and peripheral vasoconstriction, which together elevate both systolic and diastolic blood pressure.

Additional mechanisms that may contribute to the cardiovascular burden of khat use include coronary artery vasospasm, which has been implicated in case reports of acute myocardial infarction among khat chewers; platelet activation and aggregation, potentially mediated through catecholamine-induced mechanisms; and direct myocardial toxicity, suggested by animal studies showing depressed cardiac contractility following acute khat exposure.

Limitations

The review noted several important limitations in the existing evidence base. Most human studies of khat’s cardiovascular effects have been cross-sectional in design, limiting the ability to establish causal relationships. The dose of cathinone consumed during khat chewing sessions varies widely depending on the quantity of leaves chewed, the freshness and quality of the plant material, and the duration of the chewing session, making dose-response analysis challenging. Confounding factors, including the co-use of tobacco (which is common among khat users), dietary factors, and physical activity patterns, may influence the observed cardiovascular effects. Additionally, most studies have been conducted in East African and Middle Eastern populations, and the generalisability of findings to other populations requires consideration.

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