The Mantra of Medicine Buddha (藥師佛心咒)
The Medicine Buddha mantra is held to be extremely powerful for healing of physical illnesses and purification of negative karma. One form of practice based on the Medicine Buddha is done when one is stricken by disease.
Tayata Om Bekanze Bekanze
Maha BeKanze Radza Samudgate Soha (English)
爹雅他 唵 貝卡這 貝卡這 瑪哈貝卡這 拉雜薩穆 嘎喋梭哈 (Mandarin)
Tadyathā, Oṃ bhaiṣajya bhaiṣajya mahā bhaiṣajya rāja sam-udgata svāhā (Tibetan)
The practice of Medicine Buddha, the Supreme Healer (or Sangye Menla in Tibetan) is not only a very powerful method for healing and increasing healing powers both for oneself and others, but also for overcoming the inner sickness of attachment, hatred, and ignorance, thus to meditate on the Medicine Buddha can help decrease physical and mental illness and suffering.
Source(s):
Bhaisajyaguru: The Medicine Buddha
https://en.wikipedia.org/wiki/Bhaisajyaguru
https://www.buddhistdoor.net/features/the-medicine-buddha-and-the-power-of-healing