Namaskaram sidhu. I never heard of this mantra. Actually to do pancha Bhuta upasana we have omnamashivaya mantra. It is panchakshari mantra. We can also do om hrim namashivaya. This is Sakhti panchakshari. I did shakti panchakshari for nearly 6 years. It will be very good compared to ajju vijju mantra. In shakti panchakshari om refers to nirguna parabrahma tatva, hreem is maya bijam ,its for removing maya and na, ma ,shi ,va, ya these aksharas represent pancha Bhutas respectively. So if a person chants this mantra That will be sufficient. There is no mantra greater than om. But only om chanting is difficult .its difficult to control mind without Saakara Rupam. So we add saakara rupam to om and chant om namo narayana, om namashivaya etc. to reach nirguna parabrahma tatvam first we should cross panchabhutas,then maya then reach nirguna parabrahma tatvam. i think he has randomly selected this mantra,not given by a guru . It's always better to take mantras from good gurus who are trained by their gurus and belong to a good guru lineage. If we do that we will have the protection from parampara. Guru should be very strong .guru protects the shishya from doing wrongs and moving away from spiritual life. If a new born baby is there if she has a mother and father how they will take care and protect the baby,it will be like that if a person has a good guru. Since he is suffering from health problems ,it's better to change the mantra. Mananaat trayathe iti mantra they say.it means the one that gives you protection when chanted is called as mantra. We should not do which ever mantra we like . If you look at jagadguru adishankaracharya he teaches panchayatana puja vidhanam.means we can worship ganapati, shiva, ambika ,Narayana and pratyaksha daiva surya bhagavan. And subramanya has to be seen in diparadhana. These gods upasana a person has to do to attain moksha. Each gods upasana mantras and puja vidhanam will be different from others. I do shakti panchayatana, amma is my favorite goddess ,I keep her in the center and other gods idols will be around her, likewise shiva panchayatana will be there ,we keep shivlinga in center and other gods around shiva. When we do shakti panchayatana we believe that shakti is the primordial force and source of this universe and other gods are originated from her or manifested from her.it is like that. Upa plus asana is upasana. It means your mind is staying closer to the deity you worship. Every upasana should have a deity to which we are closely attached and devoted. When we are doing anything we should have clear picture of what we are doing ,why we are doing , how we are doing and what ultimately we want like this you should think and take a step forward.otherwise we get into trouble. Ask your friend to change the mantra. To which god your mind is closely attached that gods upasana you should do. In that way you can easily control your mind. Whichever gods upasana you are doing that god will be always there behind you protecting you all the time. Mantra is sound form of god. Ok. It's time for your friend to choose his favorite god and take mantra from a trusted guru and do sadhana in systematic ,disciplined manner. And also which gods upasana we do is based on our purva janma samskara. If you worshipped Narayana in your previous lives you will have a tendency to worship Narayana in this life also. It will be like that . I hope this clarifies your doubt . Sri matre Namah.