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History
The drug was first synthesized in 1962 while a chemist working for Parke Davis attempted to find a more usable sedative for work with animals and humans.  Tests on animal subjects were thought to be promising, so tests with human subjects followed.  The FDA approved the drug as a short-acting dissociative anesthetic in 1970 and it was first used during the Vietnam War to treat combat injuries.

The end of the Vietnam War in the early 1970s coincided with recreational use of the drug on the West Coast.  It was documented by several underground publications in San Francisco and was used at dance parties (eventually a rave drug) because of its powers as a hallucinogen.  The drug continued to gain popularity because it was easy to obtain and it was better controlled than PCP.  It was eventually controlled by the United States in 1999, but it continues to be a substance of choice for many as a designer-type drug.

Short-Term Effects
The effects of ketamine are related to its use as an anesthetic and that is exactly what makes this drug so dangerous.  Ketamine is meant to immobilize, to remove the sensation of pain as well as sedate a patient.  When used under controlled circumstances by a doctor or veterinarian, it is a useful tool.  However, when uncontrolled it can lead to overdose and death.

People who take ketamine recreationally report that they experience hallucinations and out-of-body sensations.  This is related to the fact that ketamine is meant to put the patient in a dream-like state.  That is what abusers of ketamine are looking for when they take the drug, but there are many adverse side effects that may occur also.

Effects vary, but it is possible that ketamine will affect every part of the body.  Depending on the physiology of the person taking the drug, they may experience either high or low heart rate (often alternating between the two) and/or high or low blood pressure.  People who are prone to undereating could experience anorexia as a result of the drug, nausea and/or vomiting.  Aside from the hallucinations that can occur even at a prescribed dose, abusers may experience double vision or tunnel vision.  Because the drug is an anesthetic, it has the effect of suppressing heart rhythms and breathing during surgery.  When the drug is taken in excess of the recommended dosage, an individual may have even greater depths of respiratory depression and feel that their airway is blocked (this occurs because the muscles also stop working as efficiently).  Another danger, especially for first time users is the danger of anaphylaxis.  It is difficult to determine if you are allergic to the drug prior to taking it, but if allergic the drug can cause a rash, swelling or a difficulty with breathing.

Long-Term Effects
Studies on the impact of long-term usage of ketamine, even at low doses, are alarming. Most of the studies show no lasting memory impairment, but they do show a greater propensity toward delusion than nonusers.  It is also more difficult for the body to both maintain and regenerate nerve tissue.  For young users, this inability of nerve cells to regenerate or grow properly, could cause developmental delays.  In tests on primates, the extended use of ketamine was shown to cause damage to the developing prefrontal cortex.

Damage to the urinary tract and liver have also been reported.  Researchers are not certain why, but many abusers report urinary tract complications from use of ketamine.  Decreased bladder capacity, incontinence, irritation of the tract and blood in the urine have all been reported consistently.  Some liver irritation has also been noted, but it seems to go away after cessation of use.  However, more study on long-term users needs to be completed to see if the liver damage is permanent over time.

Usage
Ketamine is usually injected intravenously, but the liquid form can also be drunk in a tea or some other concoction.  It is said to provide a short duration high, but it has different effects depending on the does taken.  There are four such states, the first two can lead to frightening delusions and the last two a more mellow, peaceful one:

• The “god” phase is said to be a state in which users believe that nothing can happen to them. That they have a delusional control over everything and everyone. It may also be accompanied by hallucinations of meeting God.
• K-hole is a near death experience during which the user actually thinks that they are sinking into a deep chasm. This hole is thought by many under-the-influence to be the grave.  Users report it to be a frightening and a freeing experience.
• The baby food experience is said to occur when the user experiences the immobility and helplessness of babyhood. The reason this is pleasurable is that the abuser seems to think that this state takes them back to a simpler existence.
• K-land is the mellow experience that all users are looking for when they take the drug. Users report being in a more colorful, peaceful land where there are no worries.  It is typical of drug users to want this break from reality that accompanies many usage experiences.

Conclusion
Ketamine is a medically relevant drug which is meant to assist doctors trying to achieve anesthesia in their patients.  It has the effect of immobilization and the cessation of pain desired during surgery.  Unfortunately, like most drugs, it is abused for the very reasons it is helpful.

The abuser may feel the same effects as someone who uses ketamine for surgical procedures, but they can also experience more painful or long lasting effects.  Taking ketamine without the assistance of a doctor can lead to serious cardiovascular and neuromuscular complications.  The sedation of the respiratory system can lead a user to stop breathing. The ultimate adverse effect, which happens when the user is not careful, is death.