'Ojas' is the most important factor of the body. It controlls all the physical as well as mental activities of the body. The Ojas is considered as the 'sar' i.e extract of all the sharir dhatus. According to Dalhanacharya 'Ojas' is originated from Shukradhatu. According to Sharangdhar 'Ojas' is considered as Upadhatu of Shukradhatu. According to Vaghbhat 'Ojas' is considered as Shukramala.

Types of 'Ojas'

There are two main types of 'Ojas' as follows

a) 'Par Ojas' or Excellent type of Ojas

It is situated at heart of human being. As the life is dependant on this type of Ojas it is considered as Par or Excellent type of Ojas. Person dies immidiately following loss of this Par Ojas. According to charak colour of Par Ojas is red and slight yellow. The proportion of the 'Par Ojas' in the body is considered as 8 drops according to Chakrapani.

b) 'Apar Ojas' or Secondary Ojas

It is situated in whole body. The daily activities and strength of the body is predominantly dependant on 'Apar Ojas'. Though it is present all over the body the proportion of 'Apar Ojas' is 'half Anjali'.

Properties of 'Ojas'

'Ojas' is having following properties or 'Guna' according to Charak and Sushrut

1) Guru (Heavy)
2) Shita (Cold)
3) Mrudu (Delicate)
4) Shlakshana (Soft)
5) Bahal (Heavy)
6) Madhur (Sweet)
7) Sthir (Occuping one position for long time)
8) Prasanna (Leading to excitement)
9) Picchil (Sticky)
10) Snigdha (Oily)

'Ojas' vruddhi lakshane

i.e Symptoms occur when excessive 'Ojas' is formed in the body.
When 'Ojas' is formed in excessive amount in the body following symptoms are observed.
 
1) Dehatushti i.e Good nourishment of the body.
2) Dehapushti i.e Increase in the body structure.
3) Dehabalovruddhi i.e Increase in the strength of the body.

'Ojas' kshya lakshane

i. e Symptoms occur 'Ojas' is formed in less quantity in the body.

'Ojas' kshay lakshane are described as

a) 'Apar Ojas' kshay lakshane
b) 'Par Ojas' kshay lakshane
 
According to Sushrut when 'Par Ojas' get destroyed symptoms like Murcha (Giddiness) Moha (coma) Pralap (Irrelevant speech) Mamsakshay (Flacid musle) are seen. Even death occur due to 'Par Ojas' kshay.

'Apar Ojas' kshay is desribed in follwing three stages

1) 'Ojovyapat' which leads to 'Sthabdhagurugatrata' i.e heaviness and stiffness of the body, 'Vatashofa' i.e oedema, 'Varnabheda' i.e change in complexion of the body, 'Glani' 'Tandta' and 'Nidra' i.e excessive sleep

2) 'Ojovistransa' which leads to 'Sandhivishlesha' i.e joint pain, ' Gatranamsadanam' i.e bodyache and 'Doshachyawanamkriyamassannirodah' i.e doshas of the body cannot work properly.

3)'Ojochyuti' which leads to symptoms like 'Par Ojas' kshay.

According to Charak signs and symptoms of the diminution of 'OPjas' is the feer complex, constant weekness, worry, affliction of sence organs with pain, loss of complexion, cheerlessness, roughness and emaciation.

According to Chark in the human body 'Ojas' is the first thing to be developed. This 'Ojas' is like ghee in colour, like honey in taste and like Puffed rice (laja) in odour. Foetus is formed from sperm in semen and ovum. 'Ojas' is transmitted to embryo along semen and ovum during fertilization. Thus it is considered as first thing to be developed in the human body according to Charak. Thus sutra namely 'Garbadhisarah Ojah' is famous in ayurveda.

The immunity power of the body is closely assosiated with 'Ojas'. When Ojakshay occurs human immunity decreases which leads to many infective as well as noninfective disorders. Diseases like Rajayakshma, Shosha and Urakshat are some diseases explained in ayurveda due to Ojaskshay.

Thus 'Ojas' plays vital role in normal anabo0lism, catabolism and thus metabolism of the body.