Could African Plant Medicines Follow the Cannabis Research Path?

Cannabis is one of the world’s most thoroughly investigated psychoactive plants, but it belongs to a much larger and less understood tradition of inhaled botanical medicine. Across Africa, communities have long administered medicinal plants by smoking them, inhaling steam, using smoke for fumigation, or drawing powdered material into the nose.

A new review¹ published in the Journal of Ethnopharmacology brings this fragmented knowledge together. Researchers identified 209 plant species from 72 families that are administered through the respiratory system in African ethnomedicine. These plants have reportedly been used for conditions ranging from respiratory infections and headaches to pain, seizures, insomnia, and psychological distress.

The findings do not demonstrate that all these treatments are safe or effective. Most of the underlying evidence comes from ethnobotanical surveys documenting how communities use plants, rather than controlled experiments or clinical trials. However, the review reveals an extensive body of traditional knowledge that could provide starting points for pharmacological research. Cannabis shows what can happen when one plant from that tradition receives sustained scientific attention.

A Much Larger Tradition Than Cannabis Alone

Cannabis sativa appears repeatedly in the review, including as a smoked treatment for pain and insomnia. Yet it represents only one member of a remarkably diverse African inhalation pharmacopeia.

The researchers found that Asteraceae, Lamiaceae, Euphorbiaceae, Fabaceae, and Solanaceae accounted for 34.5% of the documented plants. Leaves were the most commonly used plant part at 34.3%, followed by roots at 30.4%. Southern Africa contributed 33% of the recorded species, while Eastern Africa accounted for 22.5%.

These practices also cannot be separated neatly into modern categories of medicine, religion, and recreation. Some plants are inhaled to address coughs, asthma, tuberculosis, headaches, or pain. Others are used ceremonially, to promote calmness, communicate with ancestors, purify a person or space, or respond to culturally understood spiritual afflictions.

This overlap resembles the historical role of cannabis. Across different societies, cannabis has functioned as a medicine, intoxicant, ritual substance, agricultural crop, and cultural symbol. Accounts of traditional African cannabis use similarly show that its meaning and method of administration have varied between communities.

How African Medicinal Plants Are Inhaled

The researchers divided the documented practices into four primary administration methods. Smoking and steam inhalation were nearly equal in prevalence, followed by fumigation and snuffing.

These methods are not interchangeable. Each determines which chemicals reach the body, how quickly they are absorbed, and what unwanted substances accompany them. Smoking can deliver compounds rapidly through the lungs and into systemic circulation. Steam can extract volatile and water-soluble compounds without burning the plant. Snuff places powdered material directly against the nasal mucosa, while fumigation may expose the skin, eyes, airways, and surrounding environment.

The method is therefore part of the treatment rather than merely a traditional preference. Studying a raw plant extract may not reveal what a person is actually exposed to after the plant has been boiled, dried, crushed, or burned.

Why Combustion Changes the Medicine

One of the review’s most important observations is that heat can transform plant chemistry. Combustion does not simply release compounds already stored in plant tissue. It can break molecules apart, combine them, or create entirely new chemicals through pyrolysis.

The review describes examples in which heating produced compounds absent from the untreated plant. Smoke from Leonotis leonurus, a species sometimes called wild cannabis, contained labdane-type diterpenoids known as leoleorins A and B. Other research cited in the review found that burning particular plants created compounds with antimicrobial or sedative activity.

This presents researchers with a difficult tradeoff:

• Heat may release or create pharmacologically active compounds.
• Excessive heat may destroy beneficial volatile oils or other sensitive chemicals.
• Combustion can generate carbon monoxide, polycyclic aromatic hydrocarbons, aromatic amines, and N-nitrosamines.
• Inhaled smoke and fine particles can irritate or damage respiratory tissue.

The same tension is familiar within cannabis research. Inhalation offers rapid onset and allows users to adjust intake according to immediate effects, but burning cannabis also exposes the lungs to combustion products. The CDC warns that smoked cannabis can harm lung tissue, regardless of how it is smoked.

This has encouraged interest in controlled heating systems that release cannabinoids and terpenes without igniting the plant. The distinction between heating cannabis and burning it illustrates a broader principle that could eventually apply to other medicinal plants. If researchers can determine which temperatures release useful compounds while limiting toxic byproducts, traditional practices might inform more standardized delivery technologies.

Cannabis Provides a Research Roadmap

The review does not suggest that every inhaled plant should be commercialized or converted into a pharmaceutical product. Instead, cannabis demonstrates the research sequence required before traditional use can support modern medical claims.

Researchers must first identify the plant accurately and document how it is prepared. They must then characterize its chemical composition before and after administration, identify plausible biological mechanisms, establish dose ranges, and test for toxicity. Preclinical work may be followed by carefully designed human trials capable of measuring both benefits and adverse effects.

Cannabis has progressed much further along this path than nearly all the other species catalogued in the review. Its cannabinoids and many of its terpenes have been characterized, multiple delivery formats have been developed, and human studies have investigated applications such as pain management. Even so, cannabis still presents unanswered questions involving dosing, long-term inhalation, drug interactions, and differences between products.

If those uncertainties remain after decades of cannabis research, claims concerning lesser-studied plants require considerable caution. Traditional use can identify promising candidates, but it cannot substitute for toxicology, standardized manufacturing, and clinical evidence.

The Missing Link Is Standardization

Traditional formulations can vary according to geography, season, plant maturity, storage conditions, preparation temperature, and the knowledge of the practitioner. Two plants bearing the same scientific name may contain different concentrations of active chemicals. Two people using the same plant may also prepare or inhale dramatically different doses.

Standardization would require researchers to answer several practical questions. Which plant part should be used? Should it be fresh or dried? What temperature is appropriate? Which compounds should be measured? How much material reaches the lungs or nasal tissue? What contaminants or combustion products are present?

Researchers must also investigate herb-drug interactions. A plant that affects liver enzymes, inflammatory signaling, the nervous system, or cardiovascular function could modify the effects of prescription medications. The review concludes that the pharmacokinetics and interaction risks associated with traditional inhalation therapies remain largely theoretical and understudied.

This evidence gap is especially important because inhalation can produce rapid systemic exposure. Speed may be therapeutically valuable, but it can also make an unexpectedly potent or contaminated preparation more dangerous.

Protecting Knowledge Without Exploiting It

Drug discovery is only one part of the story. Indigenous communities have developed and preserved this knowledge over generations, while many of the plants involved are threatened by habitat loss and unsustainable harvesting. Roots and bark are particularly concerning because removing them can kill slow-growing plants.

The review notes that more than half of traditional practitioners now purchase plant material from commercial “muthi” shops because wild resources are becoming depleted. Cultivation could reduce pressure on natural populations while creating income for rural communities. However, commercialization must not separate a potentially valuable product from the people whose knowledge made its discovery possible.

The World Health Organization’s Global Traditional Medicine Strategy 2025-2034 emphasizes evidence, safety, sustainability, equity, and respect for Indigenous knowledge. Those principles offer a useful framework here. Research partnerships should include local practitioners and communities, establish informed consent, recognize intellectual contributions, and provide meaningful benefit sharing.

From Traditional Smoke to Modern Delivery

The review’s most valuable contribution is not proof that Africa contains 209 ready-made medicines. It is the identification of 209 starting points for further investigation.

The next stage should combine ethnobotany with metabolomics, toxicology, aerosol science, pharmacokinetics, and controlled clinical research. That work could determine whether specific traditional preparations contain genuinely useful compounds, whether combustion is necessary to produce them, and whether safer delivery methods can reproduce the desired chemistry.

Cannabis shows both the opportunity and the warning. A plant once understood primarily through traditional and cultural use can become the basis of an international research and product ecosystem. Yet commercialization can also move faster than evidence, leaving consumers to navigate inconsistent products and incomplete safety information.

Africa’s inhaled medicinal plants should therefore be neither dismissed as superstition nor promoted as proven therapies. They should be investigated as culturally important sources of testable scientific hypotheses. Cannabis has already demonstrated how far that process can go. The challenge now is to apply the same scientific rigor while protecting the communities, knowledge systems, and biodiversity from which the next discovery may emerge.

References:

¹ Le Roux, M. H., Adegbola, P. I., Manzini, S., Aremu, A. O., Hayeshi, R., & Pheiffer, W. (2026). African medicinal plants: An appraisal of inhalation techniques and therapeutic potential. Journal of Ethnopharmacology, 122327. https://doi.org/10.1016/j.jep.2026.122327