A suicide method is any means by which one or more persons purposely kills themselves. Suicide methods can be classified according to two modes of interrupting life processes: physical or chemical. Physical modes of interruption typically act by incapacitating the respiratory system or the central nervous system, usually by destruction of one or more key components. Chemical modes focus on interrupting biologically significant processes such as cellular respiration or diffusion capacity. Chemical methods of suicide produce latent evidence of action, whereas physical methods provide direct evidence.
Suicide by exsanguination involves reducing the volume and pressure of the blood to below critical levels by inducing massive blood loss. It is usually the result of damage inflicted on arteries. The carotid, radial, ulnar or femoral arteries may be targeted. Death may occur directly as a result of the desanguination of the body or via hypovolemia, wherein the blood volume in the circulatory system becomes too low and results in the body shutting down.
Wrist cutting is usually due to deliberate self harm rather than attempted suicide. The subject may or may not experience a noticeable release of adrenaline and endorphins. As the bleeding continues, cardiac arrhythmia is likely to ensue as the body is eventually unable to compensate. If the exsanguination is allowed to continue, the resulting severe hypovolemia will cause shock, followed by cardiovascular collapse, cardiac arrest and death.
In the case of a failed suicide attempt, the person may experience injury of the tendons of the extrinsic flexor muscles, or the ulnar and median nerves which control the muscles of the hand, both of which can result in temporary or permanent reduction in the victim’s sensory and/or motor ability and/or also cause chronic somatic or autonomic pain. As in any class IV hemorrhage, aggressive resuscitation is required to prevent death of the patient; standard emergency bleeding control applies for pre-hospital treatment.
Arterial bleeding is identified by the rhythmic gush of blood (in unison with the heartbeat) that is bright red in color. Venous bleeding, on the other hand, produces a continuous stream of blood of a darker red color. Arterial bleeding is more difficult to control and usually more life-threatening. The bleeding may be further controlled by indirect arterial pressure—for example, pressure on the brachial artery can reduce bleeding from the arm; however, pressure points should be used with caution as inadequate blood flow may cause severe damage to a limb.
Suicide by drowning is the act of deliberately submerging oneself in water or other liquid to prevent breathing and deprive the brain of oxygen. Due to the body’s natural tendency to come up for air, drowning attempts often involve the use of a heavy object to overcome this reflex. Drowning involves physical and mental anguish.
Drowning is among the least common methods of suicide, typically accounting for less than 2% of all reported suicides in the United States.
Suicide by suffocation is the act of inhibiting one’s ability to breathe or limiting oxygen uptake while breathing, causing hypoxia and eventually asphyxia. This may involve an exit bag (a plastic bag fixed over the head) or confinement in an enclosed space without oxygen. These attempts involve using depressants to make the user pass out due to the oxygen deprivation before the instinctive panic and the urge to escape due to the hypercapnic alarm response.
Helium, argon and nitrogen are commonly used in suicides by suffocation. Breathing inert gas quickly renders a person unconscious and may cause death within minutes.
Suicide by hypothermia or by cold, is a slow death that goes through several stages. Hypothermia begins with mild symptoms, gradually leading to moderate and severe penalties. This may involve shivering, delirium, hallucinations, lack of coordination, sensations of warmth, then finally death. One’s organs cease to function, though clinical brain death can be prolonged.
Suicide by electrocution involves using a lethal electric shock to kill oneself. This would cause arrhythmias of the heart, meaning that the heart would not contract in synchrony between the different chambers essentially causing elimination of blood flow. Furthermore, depending on the amount of electrical current, burns may also occur.
“The evidence here shows that electrocution inflicts intense pain and agonizing suffering,” (Justice William M. Connolly, Nebraska Supreme Court) 
Jumping from height is the act of jumping from high altitudes, for example, from a window (self-defenestration or auto-defenestration), balcony or roof of a high rise building, cliff, dam or bridge.
In the United States, jumping is among the least common methods of committing suicide (less than 2% of all reported suicides in the United States for 2005).
In Hong Kong, jumping is the most common method of committing suicide, accounting for 52.1% of all reported suicide cases in 2006 and similar rates for the years prior to that. The Centre for Suicide Research and Prevention of the University of Hong Kong believes that it may be due to the abundance of easily accessible high rise buildings in Hong Kong.
A common suicide method is to use a firearm. Generally, the bullet will be aimed at point-blank range, often at the head or, less commonly, into the mouth, under the chin or pointed at the chest. In the United States, firearms remain the most common method of suicide, accounting for 53.7% of all suicides committed during 2003.
What happens when a human gets shot will be a function of at least the missile velocity, the available energy in the projectile and the tissue interaction. A high energy firearm and proper barrel orientation to the head is likely to create devastating damage; high class hemorrhage, severe physical brain damage with permanent partial or complete tissue destruction of multiple lobes, nerve destruction and obvious skull fracture with potential bone fragments embedded in the brain; structures likely to be affected are intracranial, vascular, middle or inner ear, cranial nerve and external canal structures. With low caliber and low powered weapons, despite optimal orientation of the barrel the firearm may not be effective in killing the victim.
A failed suicide attempt by firearm may result in severe chronic pain for the patient as well as reduced cognitive abilities and motor function, subdural hematoma, foreign bodies in the head, pneumocephalus and cerebrospinal fluid leaks. For temporal bone directed bullets, temporal lobe abscess, meningitis, aphasia, hemianopsia, and hemiplegia are common late intracranial complications. As many as 50% of people who survive gunshots wounds directed at the temporal bone suffer facial nerve damage, usually due to a severed nerve.
Research published in the New England Journal of Medicine and the National Academy of Science found an association between household firearm ownership and gun suicide rates, though a study by one researcher did not find a statistically significant association between household firearms and gun suicide rates, except in the suicides of children aged 5–14. During the 1980s and early 1990s, there was a strong upward trend in adolescent suicides with a gun, as well as a sharp overall increase in suicides among those age 75 and over.
Two separate studies, in Canada and Australia, conducted in conjunction with more restrictive firearms legislation, demonstrated that while said legislation showed a decrease in firearms suicide, other methods such as hanging increased. In Australia, the overall rate of suicide actually increased (following a trend that had been moving upwards for some time), and did not decrease until measures specifically aimed at providing support to would-be suicide victims was enacted.
Research also indicates no association vis-à-vis safe-storage laws of guns that are owned, and gun suicide rates, and studies that attempt to link gun ownership to likely victimology often fail to account for the presence of guns owned by other people. Researchers have shown that safe-storage laws do not appear to affect gun suicide rates or juvenile accidental gun death.
Shotgun suicides tend to be extremely messy, and can cause body matter to go under closed doors. Suicides committed with some hollow point bullets can essentially cause the head to explode.
With this technique, the patient attempts to use some form of device around the throat to strangle and/or break the neck. In the event of death, the actual cause of death depends upon the type of hanging used, where type usually refers to the length of the drop.
In a short drop the victim may die from strangulation—in which the death may result from a lack of air asphyxiating the brain; if the former is true the patient is likely to experience hypoxia, skin tingling, dizziness, vision narrowing, convulsions, shock and acute respiratory acidosis; if the latter is true one or both carotid arteries and/or the jugular vein may be compressed sufficiently to cause cerebral ischemia and a hypoxic condition in the brain which will eventually result in or contribute to the death. In the case of a sufficiently long drop, the patient is likely to suffer a fractured 2nd and 3rd and/or 4th and 5th cervical vertebrae which may cause paralysis or death.
Hanging is the prevalent means of suicide in pre-industrial societies and is more common in rural areas than in urban areas. It is also a common means of suicide in situations where materials are not readily at hand (such as in prisons).