Before gaining enlightenment, the Medicine Buddha formed the aspiration:
May I relieve those afflicted by diseases which destroy life, destroy work, leave families broken, worse suffering and take happiness away.
May I relieve them of their disease and suffering, relieve their inner, outer and secret diseases.
May I stop natural calamities and the diseases or unhappiness arising from that. May I be the cause of people being freed from suffering.
MEdicine Buddha
This special wish was achieved upon his gaining enlightenment and he now helps us in the great capacity of a healer. In one hand, he holds an arura plant, known for its healing powers; in the other, a begging bowl filled with medicinal substances to show that he brings us healing, medical help and relief.
He is extremely efficacious for both people within the healing profession (doctors, nurses, healers, psychologists etc) and people seeking right doctors, treatment, diagnosis, healing and effective medicine. He has the ability to stop natural calamities and the negative, diseases or suffering arising from them.
The Medicine Buddha’s body is a cool soothing blue like that of lapis lazuli, representative of the energy of healing for he heals us on various levels. Outwardly, he helps to overcome disease and the suffering causes by disease.
On an inner, deeper level, he heals us by ultimately destroying the diseases of our mind. His practice helps us cut off our self-cherishing mind and destroys our ignorance (the root of all our suffering) by showing us the way to realise Dharmakaya (emptiness).
Practice to him ensures faster recovery from illnesses, the blessing of medicines, strength and clarity of the mind to bring you peace in your heart.
His spiritual energy in the form of sound that helps to transform the mind (Mantra):
TAYATHA OM BEKANZE BEKANZE MAHA BEKANZE BEKANZE RAJA SAMUGATHE SOHA
Extracted from http://resources.tsemtulku.com/buddhas/lower-tantra/medicine-buddha.html