Low-dose ketamine is generally well-tolerated when administered under medical supervision, but it can cause a range of mild to moderate side effects, most of which are temporary and resolve within a few hours after treatment[1][3].
Common side effects include:
- Dissociation (a feeling of being disconnected from one’s thoughts, body, or surroundings)
- Drowsiness or sedation
- Dizziness
- Nausea and vomiting
- Anxiety or transient mood changes
- Blurred vision
- Difficulty speaking or temporary speech changes
- Increased heart rate and blood pressure during the infusion
- Headache
- Disorientation or confusion
- Feeling “strange,” euphoria, or vivid dreams
- Numbness or sensory changes
- Trouble with balance or coordination
These effects most often occur during or shortly after ketamine administration and typically resolve within 4 hours[1][3][11].
Less common side effects may include:
- Hallucinations or visual disturbances
- Nightmares
- Temporarily increased saliva
- Jerky or uncoordinated movements
- Fast eye movements or double vision
- Rash, pain, or redness at the injection site
- Delirium or low mood
- Brief blood pressure spikes or irregular heart rate
Rare or serious side effects (particularly with higher doses or in susceptible individuals):
- Respiratory depression (significant slowing of breathing)
- Cystitis (bladder inflammation; generally occurs with long-term or high-frequency use)
- Dependence or misuse (usually linked to recreational use, not therapeutic dosing)
- Allergic reactions including rash or anaphylaxis (very rare)
Serious side effects, such as severe cardiovascular or psychiatric complications, are much less likely at the lower doses used for mood disorders and are more common at anesthetic doses[3][11]. Careful patient screening and monitoring minimize these risks, and ketamine is not recommended for individuals with uncontrolled hypertension, schizophrenia, or a history of substance misuse[11].