Suicide postpones and intensifies negative karma, and Dharma ethics do not condone deliberately causing the death of a person at his/her request by any lethal means. Dharma practitioners may describe —but never enthusiastically recommend— voluntary fasting unto death and powa (the yoga of consciousness transference) as viable means to abbreviate prolonged suffering in the dying.
After due deliberation, voluntary fasting unto death or powa should be undertaken as spiritual practices, with the support of a community of faith. Voluntary fasting and powa are allowed when the person is unable to perform normal bodily purification, death appears imminent, and pain and suffering are extreme, such that mitigating them would entail loss of consciousness.
The dying person must declare his or her wishes publicly, to distinguish the act from suicide committed secretly in traumatic emotional states of anguish and despair, and to allow for family and community intervention.
(Voluntary fasting is gradual, and allows the person to reconsider his/her decision. Although powa is sudden, its practice requires extensive preparation, indicative of a clear mind, free of agitation.)