Risks and Side Effects of Ketamine Treatment: What You Need to Know

What You Should Know Before Starting

Ketamine therapy has shown remarkable results for treatment-resistant depression, anxiety, and PTSD. But like any medical treatment, it comes with potential side effects. Understanding these — and knowing which are common, which are rare, and which require attention — is essential for making an informed decision.

Common Side Effects

Most side effects are temporary and resolve as the medication clears your system, typically within 1–2 hours.

Dizziness or lightheadedness — Disorientation during or shortly after a session is normal. It subsides as effects wear off.

Blurred vision — Usually short-lived and mild. It resolves on its own.

Nausea or vomiting — One of the most commonly reported effects. It's well-understood and highly manageable with fasting, anti-nausea medication, and proper positioning.

Elevated heart rate or blood pressure — Temporary increases are common and typically resolve within the session. Patients with hypertension should have their blood pressure monitored.

Changes in perception — Altered sense of time and space, visual distortions, or feeling detached from reality. These are expected parts of the dissociative experience and resolve fully.

Psychological discomfort — Some patients experience brief anxiety or unease during the session. This almost always resolves as effects wear off.

Rare but Serious Side Effects

These are uncommon, particularly when ketamine is used as prescribed under medical supervision:

Psychotic symptoms — Patients with a history of psychosis or schizophrenia should not receive ketamine. This is a contraindication.

Muscle contractions or seizures — Extremely rare, but require immediate medical attention.

Respiratory issues — Laryngospasm, respiratory depression, or apnea are very rare at therapeutic doses. They demand urgent intervention if they occur.

Urinary problems — Bladder irritation, frequent urination, or discomfort. More common with chronic recreational use and extremely rare when taken as prescribed.

Increased eye pressure — Temporary and generally benign. Rare at standard doses.

Addiction potential — Ketamine is a Schedule III controlled substance. Risk of dependence is low when used in a structured medical program, but it's a real consideration for patients with a history of substance use.

When to Contact Your Provider

Reach out if you experience:

• Vomiting that prevents fluid retention
• Nausea or symptoms lasting beyond 4–6 hours after a session
• Symptoms between sessions that weren't present before
• Severe abdominal pain
• Worsening symptoms despite preventive measures

Minimizing Risk

The most effective way to minimize side effects is working within a structured treatment program:

• Follow fasting guidelines before sessions
• Use prescribed anti-nausea medication when recommended
• Have a peer supervisor present during every session
• Maintain open communication with your provider about medication interactions
• Follow post-session instructions for rest and recovery

The Perspective

Most side effects from ketamine therapy are mild, predictable, and temporary. Serious effects are rare and typically associated with misuse rather than supervised treatment. The risk profile compares favorably to many conventional antidepressants, which carry their own significant side effects including sexual dysfunction, weight gain, and withdrawal symptoms.

That said, ketamine isn't appropriate for everyone. For a full overview of when treatment should be avoided, see when ketamine is not appropriate.