Medicine Buddha is found in the Mahayana (and therefore Vajrayana) traditions. The Medicine Buddha Sutra is widely recited. Medicine Buddha is said to have made 12 vows when he was a bodhisattva, whose effects we now experience. The Vajrayana tradition has various sadhanas of Medicine Buddha. In Mahayana, he is depicted with a bowl of medicine but no other specific features. In Vajrayana, he holds a bowl of medicine in his left hand, an arura plant in his right. He is the colour of lapis lazuli. In Vajrayana, there are six other Medicine Buddhas, but the main one is the one described above. Sometimes, Shakyamuni Buddha is considered to be the eigth.
In the attached images, the first has Medicine Buddha and the other seven Buddhas above him. At the top are the 16 great bodhisattvas, an extension of the eight mentioned in the sutra. The sutra specifically mentions Manjushri and Kyab Drol (Tibetan name. The Sanskrit translation would be The Bodhisattva Who Rescues and Liberates). Then the 32 yaksha generals, an extension of the 12 yaksha generals found in the sutra. The other yaksha generals are comprised of the four directional guardians and other deities. This is also the way his mandala is depicted.
The most common version of his dharani is
OM NAMO BHAGAVATE BHAISAJYE GURU VAIDURYA PRABHA RAJAYA TATHAGATAYA ARAHATE SAMYAKSAM BUDDHAYA TADYATHA OM BHAISAJYE BHAISAJYE MAHA BHAISAJYE RAJA SAMUDGATE SVAHA