Ketamine Therapy Side Effects
Mild, Manageable, and Gone in Hours
Most side effects of ketamine therapy occur on the day of treatment and resolve quickly, often within hours. Here’s what you might experience:
Common Day-of Treatment Side Effects
- Drowsiness
- Fatigue
- Lightheadedness
- Difficulty balancing
- Temporary increase in blood pressure (during or after treatment)
These effects are short-lived, usually clearing up within 3–4 hours. Mild sedation or fatigue may linger for the rest of the day but typically fade by evening.
I Liked My Side Effects
All those side effects you just read above? I experienced all of them. The only difference is that after the first couple of hours I would describe my experience as entering a state of “what me, worry?” mellowness—an almost pleasant tiredness. I found it hard to get angry, stressed or anxious (God, if I could only bottle that feeling!).
Here’s something you should know: for the first few hours after treatment, it’s nearly impossible to work, concentrate, or focus on anything. That’s one of the biggest drawbacks of ketamine therapy—maybe the drawback. When you factor in travel time, the session itself, and the recovery period, you’ve pretty much lost most of the day to do anything important.
Occasional Day-of Treatment Side Effect
About 7% of patients report nausea or vomiting during treatment. However, this can often be prevented by:
- Fasting for six hours before treatment
- Taking anti-nausea medication
From Queasy to Constipated
I definitely felt nauseous an hour or two after my first ketamine session. Luckily, my psychiatrist had given me a prescription for Zofran (ondansetron), but here’s the catch—it didn’t work all that well because I took it after I started feeling sick. Rookie mistake.
Once I learned to take it before the session, the nausea improved, but it didn’t disappear entirely. Eventually, I doubled the dose, and that did the trick—I never experienced nausea again. But then came the trade-off: Zofran put me squarely in the 9–11% of people who get constipated. So there I was, balancing it out with laxatives and, God help me, eating a lot of prunes.
I won’t lie—it was a hassle. But I seem to be in the minority here. Statistically and anecdotally, most people don’t need anti-nausea meds for ketamine therapy, and even if they do, they usually don’t deal with constipation. I’ve got a few friends who went through ketamine therapy, and none of them had the same issues I did.
Rare Side Effects of Ketamine Therapy
I’ll admit, I had reservations about writing this section. Rare side effects are tricky to talk about because no matter how many times you say “rare,” people tend to latch onto them and think, If they’re mentioning it, it’s probably going to happen to me.
I get it—listing side effects can be scary. It’s like those drug commercials on TV where half the ad is a rapid-fire list of terrifying things that could happen, leaving you wondering why anyone would risk taking it. The truth is, those lists are there because the law demands it, not because the risks are common. The same goes for ketamine therapy.
Rare side effects are exceedingly uncommon, and in most cases, they happen when ketamine is misused—through illegal dosing or excessive use as a party drug. In a controlled clinical setting, with the low doses used to treat depression, these side effects are highly unlikely. But if you’re going to trust the process, it’s important to have all the facts. So, let’s talk about them.
One of the rare side effects you might hear about is ketamine-induced cystitis, which can affect the bladder. Symptoms include urinary frequency, urgency, or discomfort, but here’s the thing: this condition is typically seen in people abusing ketamine at much higher doses than you’d ever get in a therapeutic setting. In the rare instances where bladder issues appear during depression treatment, they usually resolve once the therapy is stopped.
When You Gotta Go You Gotta Go
During my first couple of ketamine sessions, I had such an urgent need to pee that it completely distracted me from the journey. I’d be mid-session, trying to stay present, and all I could think was, “I need to pee!”
The clinic mentioned that a few other people had experienced the same thing, but it wasn’t common. There’s not much you can do to eliminate it entirely, but I found a couple of tricks that helped: I stopped drinking water for a few hours before the session, and I always made sure to hit the bathroom right before the ketamine was administered.
These little adjustments made all the difference, letting me fully settle into the experience without distraction.
Another Rare Side Effect
It’s a temporary elevation in liver enzymes. This one rarely causes symptoms and is often only noticed through routine blood tests. It’s something your care team might monitor if you’re undergoing long-term treatment, but for most people, it’s a non-issue.
There have also been very rare reports of prolonged psychological effects, like confusion, paranoia, or hallucinations, lasting beyond the treatment session. Again, these are incredibly rare and tend to resolve on their own or with slight adjustments to your treatment plan.
Finally, long-term or high-dose use of ketamine—like the kind seen in recreational settings—has been linked to cognitive changes, such as difficulty with memory or attention. But this is almost unheard of in therapeutic protocols, where doses are tightly controlled.
Pay These Rare Side Effects Little Mind
I know how easy it is to focus on the worst-case scenarios, but the reality is that these side effects are incredibly rare when ketamine is administered safely and professionally. The best analogy I can give is that these risks are like getting struck by lightning—not impossible, but highly unlikely, especially if you’re not standing in the middle of a storm.