The two basic aims of Ayurveda are prevention and curing of diseases. Both the preventive and curative aspects can be achieved mainly through the apt use of various drugs. In order to yield better result various drugs are used in combination with others. To be more specific to the condition of the person undergoing treatment various aacaaryas has mentioned about various modes of preparation or forms of medication. Eg. Kashaaya (decoction), arishta (fermented preparation), aasava (fermented preparation), taila (oil), ghrta (ghee), lehya (linctus) etc are the various forms of medication. Among these lehya has its own reason to be considered as one of the important form of medication in Ayurveda.
Avaleha or lehya is a semisolid form of drugs, prepared with addition of jaggery, sugar or sugar candy and boiled with prescribed juices or decoction.
It may also be defined as a preparation which could be licked.

This preparation is also known under various names like leham, leha, rasakriya, kakavi.
The term ‘kakavi’ has been used by aacaarya Dalhana while the term ‘rasakriya’ has been mentioned by aacaarya Saarnggadhara.
Method of preparation
The drugs needed for a specific formulation are collected. These drugs could be broadly divided into two.
The major drugs which are of prime importance (powders or pulps of certain drugs).
The sweetening agents – these include sugar, sugar candy and jaggery.
Ghee is also used which keeps the lehya soft and also helps in preserving it.
The quantity of sweetening agents used also needs a special mention. If sugar candy is used as a sweetening agent, its quantity should be four times the quantity of drugs. In case of jaggery, it should be double the quantity.
The major drugs are dried, finely powdered and sieved through a clean cloth individually as well as collectively. The ingredients mentioned in the recipe are taken and made into kashaaya (decoction). Sugar, sugar candy, jaggery etc. are added and it is filtered once

more to remove the foreign particles. It is then kept over mandaagni( mild fire) and subjected to continuous stirring until it reaches a semisolid stage and form thread like extensions when pressed and drawn between the thumb and index finger.
Ghee or oil if mentioned is added while the preparation is still hot and is mixed well. Madhu (honey), if mentioned is added when the preparation is cool and is mixed well. When metals are mentioned, the bhasma of those metals are used. If poisonous drugs like bhallataka (Semicarpus anacardium) are mentioned, proper purification should be done before adding them.
According to aacaarya Saarnggadhara, properly prepared avaleha has to fulfill the following tests.
Tantumatvam : Should have thread consistency when pressed between the fingers.
Apsumajjati : If put in water, should sink in it.
Kharatvam : Solid/rough to touch.
Peeditomudra : Should give fingerprints when pressed between fingers.
Gandha varna rasodbhavatvam : Must attain the odor, color and taste of its ingredients.

According to aacaarya Saarnggadhara one pala (forty eight gram) is the dose for avaleha. But according to aacaarya Yaadavji, the dose is one karsha (twelve gram).
Various aacaaryas might have mentioned dosage of avaleha according to the agni bala (digestive power) of the concerned person. In case of pravara agni (increased digestive power), madhyama agni (moderate digestive power), and avara agni (decreased digestive power) the dose would be two pala, one pala and one karsha respectively.
Time of administration
According to bhaishajyaratnaavali if the patient is affected with a disease in his oordhvajatrugata bhaaga (part of body above neck), avaleha should be given at saayamkaala (evening time) with proper anupaana (post prandial drink). But if the disease affects his adhobhaaga (remaining part of body), taking avaleha before food is better.
Anupaanas differ according to the disease. Commonly used anupaanas according to aacaarya Saarnggadhara are ksheera (milk), ikshu rasa (sugarcane juice), yuusha (soup made of pulses) and kashaaya (various decoctions). Jala (water) and phalarasa (fruit juice) has also been mentioned in dravyaguna vijnjaana.

Storage and shelf life
Avaleha should be stored in glass, porcelain or metallic containers which do not react with the drug.
Shelf life depends on the quantity of sugar, sugar candy or jaggery added. Its usual shelf life is up to one year.
Avaleha, due to its good palatability is widely accepted among all age groups. It is easily consumable and is rich in taste. The metabolism and absorption of this pharmaceutical form starts from the mouth itself because of presence of more quantity of glucose, fructose etc. The acceptance of avaleha is more in comparison with the other varieties of Ayurvedic medication.
Standardization parameters.
The description of the preparation in terms of its color, odor, taste and consistency is very important. Various other clinical tests like loss on drying at 105°c, total ash value, pH value, total solid content, fat content, total sugar content, tests for heavy/toxic metals etc may also be done.

Commonly used formulations
The various commonly used avaleha formulations are Cyavanapraasarasaayana, agastya hareetaki, brahma rasaayana, vilvaadi lehya, koosmaanda avaleha, vyaakhri hareetaki etc.

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