• headaches
• flashbacks
• loss of sense of smell (due to snorting)
• educed memory function and other impairments in thinking
• personality and mood changes
• depression
• impaired concentration

Ketamine bladder syndrome

Many of the short-term harms and risks are some of the effects sought by the users of the drug:

• There is evidence that after frequent and prolonged use, ketamine is addictive.
• People who use ketamine regularly can develop dependence and tolerance to it, which means they need to take larger amounts of ketamine to get the same effect.
• Dependence on ketamine can be psychological, physical, or both.
• People who are dependent on ketamine find that using the drug becomes far more important than other activities in their life. They crave the drug and find it very difficult to stop using it.

Ketamine is a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, but at higher doses may also bind to the opioid mu and sigma receptors. It is related to phencyclidine (PCP), but has less than 10 percent of the potency of pure PCP

http://www.drugs.com/ketamine.html

• The effects of ketamine can last for approximately 45 to 90 minutes.
• As the effects of ketamine begin to wear off, a person may experience a range of effects.
• These effects can last for approximately 24 hours and can include:
  • memory loss
  • impaired judgement
  • poor coordination
  • general aches and pains
  • disorientation

     

• Ketamine can be swallowed, snorted or injected.
• It is also sometimes smoked with other substances such as cannabis or tobacco.
• The effects of ketamine may be experienced within 30 seconds (if injected) up to 20 minutes (if swallowed) and 5–10 minutes (if snorted).

• respiratory depression
• elevated heart rate
• seizures
• coma
• death

http://www.drugs.com/ketamine.html

• A high dose of ketamine can cause a person to overdose. This means that a person has taken more ketamine than their body can cope with.
• The risk of overdose increases if the strength or purity of the ketamine is not known.

High doses of ketamine can intensify some of the effects experienced at lower doses. People may also experience:

• feelings of euphoria and relaxation
• feelings of being detached from the body sometimes known as 'falling into a k-hole'
• hallucinations and distorted perception, including visual, auditory, physical, time and space
• disorganised thoughts, confusion and difficulty concentrating, thinking or maintaining attention
• anxiety, agitation, paranoia and feelings of panic
• slurred speech
• blurred vision
• constricted (small) pupils
• lack of coordination
• increased but shallow breathing rate