Oral vs IV vs IM ketamine: the real differences
Oral lozenges, intranasal, intramuscular injection and intravenous infusion all deliver ketamine - but the experience, the onset, the clinical evidence and the price are not the same. A practical comparison.
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TL;DR
- IV is the best-studied route for depression. Onset is minutes; session ~45 min.
- IM has comparable efficacy to IV and costs less. Session ~60 min, slightly longer afterward.
- Oral/lozenge has less evidence but works at home with a remote prescriber for mild-to-moderate depression.
- Intranasal (compounded, not Spravato) is rarely recommended; absorption varies too much.
Ketamine is the same molecule whether you take it as a pill, a spray, an injection or an infusion. What changes is bioavailability, speed of onset, dose control, session experience and cost. Here is what you need to know about each route to pick the one that fits your situation.
Intravenous (IV)
IV ketamine is the best-studied route for treatment-resistant depression. An infusion typically runs 0.5 mg/kg over 40 minutes, with the patient monitored continuously. Onset is within minutes; the dissociative experience peaks around minutes 10-30 and tapers over the next hour. Clinics bill $400-$600 per session.
Pros: complete dose control, fastest onset, strongest evidence base. Cons: highest cost, requires venipuncture, clinic-bound.
Intramuscular (IM)
IM injection (usually in the deltoid or gluteus) is a single-dose administration of 0.5-1.0 mg/kg. Onset is slightly slower (5-10 minutes) and the dissociative window a bit longer. Efficacy appears comparable to IV for depression in emerging literature. Sessions run $300-$450.
Pros: lower cost, no IV line, still excellent dose control. Cons: less fine-grained titration; if the dose is too high, you cannot reduce mid-session.
Oral lozenges
Compounded oral ketamine troches (typically 100-400 mg) are prescribed for at-home use, usually through a telemedicine service combined with remote therapy. Bioavailability is ~20-30% (much lower than IV/IM), onset is 20-40 minutes, and the experience is milder. Evidence is thinner than for IV but positive, particularly for mild-to-moderate depression when combined with psychotherapy.
Pros: lowest cost ($150-$300/month including the remote care), in your own home, compatible with therapy. Cons: less evidence in severe depression, slower onset, variable absorption, requires a safe set-and-setting at home.
Intranasal compounded
Not Spravato - this is compounded racemic ketamine spray prescribed off-label. Absorption varies 20-50% between individuals, making dosing imprecise. Most ASKP3 prescribers avoid this route in favor of IV, IM or oral.
Which to pick
If you have severe or treatment-resistant depression, IV is the default and has the strongest evidence. IM is a reasonable substitute if cost is a barrier. Oral lozenges are a real option for mild-to-moderate depression, especially when paired with ongoing psychotherapy. Avoid compounded intranasal unless a trusted clinician has a specific reason.
What to ask the clinic
Whichever route, the baseline monitoring standards apply: someone in the room with BLS/ACLS certification, continuous vital-sign monitoring, an integration plan, and a documented escalation protocol. The route of administration is a detail; the clinical quality is the question that actually matters.