Cannabis sativa L., an annual dioecious herb of the family Cannabaceae, is known globally as marijuana or Indian hemp and locally in Nigeria as “Igbo,” “wiwi,” and “ebo”. Native to Central Asia, it is now cultivated worldwide (1, 2) and used recreationally and medicinally for its phytoconstituents and cannabinoids, with applications ranging from analgesic to anti-inflammatory effects (2-4). Commonly smoked, it is also brewed as tea, infused in alcohol, added to food, or eaten fresh (5, 6). Nigeria ranks among the largest producers, suppliers, and consumers in West Africa (7-9). Despite its illegal status, documented use persists (10, 11). Globally, 147 million people (2.5% of the population) use cannabis, with an estimated 50,000-100,000 diabetic patients consuming it, rising from 1.7% in 2005 to 5.8% in 2018, with an unknown number self-medicating (12, 13). While bioactive plants are well represented in orthodox medicine, data on the safety and phytochemical profile of locally cultivated cannabis remain scarce. Most toxicity studies have focused on isolated cannabinoids, synthetic derivatives, or certified extracts (14), leaving a gap in knowledge regarding repeated oral administration of the crude extract. This study fills that gap by identifying the phytoconstituents and cannabinoids of an indigenous Nigerian variety and assessing its toxic effects in Wistar rats to guide dosing for future efficacy studies and evaluate potential histopathological changes in vital organs.

The global rise in cannabis use is especially notable in Nigeria, where our unique local variety is gaining popularity (9, 20). This rise in traditional oral consumption–whether as tea, infusions in alcoholic drinks, or as condiments and vegetables in soups– along with the use of crude plant extracts instead of pharmaceutical-grade products, influenced the decision to use crude ethanol extract and the oral route for this study (6, 9). However, there is limited data on its phytocannabinoids and the toxic effects of repeated oral intake.

The preliminary and FTIR analysis of the ethanol extract from C. sativa leaves confirmed the presence of several secondary metabolites, consistent with similar studies highlighting the complex nature and therapeutic effects (1, 6). The high THC levels detected by GC-MS analysis, with a (THC+CBN/CBD) ratio of >1 and a CBD/THC ratio of <0.5 (0.11), classify this local cannabis as chemotype 1 and drug-type (narcotic) according to chemotaxonomic classification (6, 21-23), suggesting a potential for toxicity. Therefore, classifying cannabis chemotypes can help predict both therapeutic and adverse effects. The observed THC levels are consistent with other studies that reported elevated levels in cannabis products, which might be due to the degradation of tetrahydrocannabinolic acid (THCA) and influenced by regional climate.

The acute toxicity profile showed effects varied with dose, with high doses causing excitatory effects, while inhibitory effects occurred at lower doses. These findings align with the literature, which emphasizes the plant’s complexity, making classification as a stimulant or depressant difficult (24, 25), with effects varying by dose, strain, and genetic factors. The lethal dose 50 (LD₅₀) of C. sativa, which exceeds 5000 mg/kg after oral consumption, is regarded as safe according to established standards for chemical substances (17).

Subacute toxicity studies are crucial for predicting the safety of agents administered repeatedly, as they evaluate the structural integrity and function of organs through biochemical analysis (17). The observed dose-dependent weight loss agrees with other studies that report reduced body mass index (BMI) and lower rates of obesity in cannabis users (26, 27), thereby increasing interest in its potential for weight management. However, further research is necessary to explore the long-term effects on appetite-regulating hormones.

Repeated administration of C. sativa extract did not significantly alter liver function markers, as the observed reductions in ALP and ALT levels and increase in AST values remained within accepted ranges (28, 29). However, the mild necrosis observed in liver tissue samples across treatment groups may suggest limited safety after repeated exposure.

The elevated plasma urea levels in animals receiving 250 mg/kg could result from dehydration, as histological examination showed mild tubular changes. The significant increase in glucose levels in the 125 and 250 mg/kg groups remained within normal ranges (30, 31).

The toxic effects of xenobiotics and chemicals on cardiac and skeletal muscle membranes can be assessed by plasma levels of creatine kinase (CK) and lactate dehydrogenase (LDH), which act as biomarkers of muscle damage because they cannot cross the sarcoplasmic membrane (32). The observed increase in LDH levels and decreased CK levels suggests toxic effects on muscles and tissues, indicating potential damage to the organs.  

The impact of crude plant extracts on the lipid profile after oral administration is essential for predicting cardiovascular risk, with the subacute use of C. sativa crude extract resulting in decreased LDL and triglyceride levels in the 250 mg/kg treatment group, with LDL levels within the optimised range for female Wistar rats (31, 33).

Blood parameters, including hemoglobin, haematocrit, red blood cells (RBC), and white blood cells (WBC), reflect health status with deviations indicating toxicity or disease conditions (28, 34). Repeated administration of C. sativa crude extract led to increases in PCV, hemoglobin, mean corpuscular hemoglobin concentration, and neutrophil levels, suggesting erythrocytosis (30, 31, 34).

Changes in organ weight indicate toxicity, which may result from damage, enzyme disruption, or physiological disturbances, and are confirmed through gross examinations, clinical evaluations, and histopathological analyses (17). Mild to moderate changes in the structure of the pancreas, kidney, and liver confirm the non-lethal toxicity profile of the C. sativa crude extract. However, the elevated levels of some observed parameters highlight the importance of regular monitoring of individuals using C. sativa over an extended period.

The results of this study demonstrated the relative safety of the crude ethanol extract of C. sativa after consumption, with an oral LD₅₀ of >5000 mg/kg body weight (GHS-Category 5, LD₅₀ cut-off at 5000 mg/kg body weight) and a NOAEL dose of ≤300 mg/kg body weight. These results suggest that our indigenous variety of C. sativa may be considered safe for oral intake, despite the behavioral changes and significant weight loss observed in the animals.