Toxicity of Ayurveda medicines and safety concerns: The need to revive the branch of toxicology in Ayurveda

Prayogaḥ śamayedvyādhimekaṃ yo’nyamudīrayet|

Pnāsau viśuddhaḥ śuddhastu śamayedyanna kopayet||

Aṣṭāṅgahṛdayasaṃhitā, Sūtrasthāna, 13.16

A resurgent Ayurveda is sought after as a safer alternative to chemical medicines. In fact, the adverse effects of modern drugs have triggered a search for medicines from natural and safer sources, thus bringing traditional systems of medicine into the limelight. The perception is that medicines derived from plants processed in crude form without the isolation of the active molecules would be safer.

The tables have turned against traditional systems of medicine like Ayurveda after being subjected to suspicions of toxicity of its medicines.[1] Just as there are questions about efficacy of Ayurveda, the perception is being built that Ayurveda by itself does not have adequate protocols to identify and check the toxicity of its medicines.

It is pertinent to point out that Ayurveda is perhaps the earliest system of medicine to have developed the specialized discipline of toxicology. Toxicology or Agada Tantra is one of the eight clinical specialties of Ayurveda since thousands of years.[2] The present educational system is just paying lip service to Agada Tantra and it seems that this discipline is going to be demoted as a nonclinical subject in the Ayurveda curriculum. Those trained in this branch are mainly dealing with forensic medicine.

Agada Tantra has often been exclusively associated with healing cases of envenomation. With the advent of modern treatments for snake bites and the relative decrease in such incidents, this branch of Ayurvedic treatment is now considered to be obsolete and is being sidelined in the modern institutions of Ayurveda. This is in spite of the fact that there are traditional practitioners in parts of Kerala and other remote areas in the country who still practice many techniques of Agada Tantra even today.[3]

By definition, Agada Tantra deals with poisoning by bites of venomous creatures and also poisoning from other sources. Ayurveda distinguishes between two types of poison – the one of animal origin (jaṅgama) and the one of plant origin (sthāvara). Sometimes, a third category of artificial poison (kṛtrima) is also enumerated.[4] The time is ripe to revisit the Agada Tantra of Ayurveda variously known as Viṣacikitsā and Garacikitsā to face the challenges posed by the growing concern of the toxicity of Ayurvedic medicines.

Safety of medicines and treatments has always been on high priority in the tradition of Ayurveda. Ayurveda has taken pride in claiming itself to be the śuddha approach to treatment that pacifies diseases without causing new problems. A treatment or medicine, that cures one disease and gives rise to another, is considered to be aśuddha or impure.[5]

Ayurveda has looked into toxicity of so many things under the sun that can affect human health adversely. There is even a term for toxic air (viṣavāta),[6] not to speak of food, safety of which has been considered to be of paramount importance in Ayurveda. In classical textbooks of Ayurveda, separate chapters have been devoted exclusively for food safety (annarakṣā).[7] Even foods such as milk and ghee that are commonly consumed in the day to day life have been characterized as toxic in certain contexts. Ghee or milk consumed when the digestive fire and metabolism is on a low ebb works like poison (viṣopamam).[8] We can see that Ayurveda has given red alerts about commonly used items like pepper, which can work as irritants on long term use.

When it comes to medicinal plants, toxicity of poisonous plants, have been well-described. Plants like Plumbago rosea and Acorus calamus which are commonly used in Ayurvedic formulations are to be used only after purification. Ayurvedic texts distinguish poisonous substances to be either toxic or semi-toxic and lethal or nonlethal. Poisons can also be slow acting or fast acting on the body.[9]

Poisons, which remain in the body for a long period of time and cause intractable diseases, are known as garaviṣa.[10] Intentional poisoning, to harm other fellow human beings, gives rise to the formulation of artificial poisons. A physician had to know about such substances and the remedies for them.

Ayurvedic texts have listed antidotes for many commonly known poisons from both the animal and plant kingdom. When it comes to the use of minerals and metals, the texts are clear that these are extremely toxic substances that can have a fatal impact on the body. However, elaborate methods of purification and processing have been described to render them nontoxic and safe for human use.

The adverse effects of treatments are also very well described in the texts and iatrogenic diseases caused by improper treatment are described very early in the evolutionary history of Ayurveda.[11]

A close study of the texts reveals that Ayurveda has looked at toxic effects of substances and their impact on human health in a multifaceted manner. There is a need today to reconstruct the Ayurvedic discipline of toxicology to deal with the challenges that Ayurveda faces today with regard to the safety of its medicaments and treatments. In other words, there is a need to resurrect and nurture the Ayurvedic toxicologist to develop an insider's view and come up with solutions to safety concerns in the practice of Ayurveda.

Not only is there scope for Ayurveda to find solutions for toxicity issues related to Ayurveda, but there is also great scope for discovering solutions to new challenges in toxicity that have emerged in the modern world. Environmental pollution, use of harmful pesticides that contaminate natural sources of human food and the use of chemical cosmetics have created new health issues for humanity. There is a good chance that Ayurveda can discover solutions for these problems.

Another area, where Ayurvedic toxicology can make valuable contributions, seems to be the toxicity of modern drugs. We hear anecdotal accounts of how the toxicity of chemotherapy and radiation therapy could be mitigated by adjuvant Ayurvedic treatment. This area needs to be further explored and developed.

To sum up, we can say that Ayurvedic physicians must develop a clear perspective of the safety of Ayurvedic medicines and treatments and find solutions from within. The Ayurvedic toxicologist well trained in Agada Tantra seems to be the answer. An exhaustive listing of all potential hazards associated with Ayurvedic treatments, guidance on how to anticipate them and also manage them would be the first step in this direction.

Just as in the case of generating evidence on efficacy of Ayurvedic treatments, a three-pronged strategy is recommended for generating evidence on the safety. The primary evidence will come from the codified texts and the secondary evidence from the living practices. Tertiary evidence from modern scientific research will serve to fill the gaps.