Survey Results On SSRIs · Read Scott Alexander

SSRIs are the most widely used class of psychiatric medications, helpful for depression, anxiety, OCD, panic, PTSD, anger, and certain personality disorders (Why should the same drug treat all these things? Great question!) They’ve been pretty thoroughly studied, but there’s still a lot we don’t understand about them.

The SSC Survey is less rigorous than most existing studies, but its many questions and very high sample size provide a different tool to investigate some of these issues. I asked fifteen questions about SSRIs on the most recent survey and received answers from 2,090 people who had been on SSRIs. The sample included people on all six major SSRIs, but there were too few people on fluvoxamine (15) to have reliable results, so it was not included in most comparisons. Here’s what we found:

1. Do SSRIs work?

People seem to think so:

Made me feel much worse: 6%
Made me feel slightly worse: 7.4%
No net change in how I felt: 23.7%
Made me feel slightly better: 41.4%
Made me feel much better: 21.4%

Of course, these statistics include the placebo effect and so cannot be taken entirely at face value.

2. Do some SSRIs work better than others?

I asked people to rate their experience with the medication, on a scale from 1 to 10. Here were the results:

Lexapro (356): 5.7
Zoloft (470): 5.6
Prozac (339): 5.5
Celexa (233): 5.4
Paxil (126): 4.6

Paxil differed significantly from the others; the others did not differ significantly among themselves. In a second question where participants were just asked to rate their SSRIs from -2 (“made me feel much worse”) to +2 (“made me feel much better”), the ranking was preserved, and Lexapro also separated from Celexa.

This ranking correlates at r = 0.98 (!?!) with my previous study of this taken from drugs.com ratings.

I don’t generally hear that Paxil is less effective than other SSRIs, but I have heard that it causes worse side effects. The survey question (probably wrongly) encouraged people to rate side effects as “negative efficacy”. My guess is that the difference here is mostly driven by side effects.

3. Do SSRIs work better for anxiety than for depression?

I’ve heard a few people mention this, and it makes sense as one reason why they remain so popular among patients and doctors while rarely producing large effects on specialized depression tests.

On the same scale as above:

Anxiety (391): 5.9
OCD (24): 5.8
Depression (1203): 5.3
Panic (26): 5.5
Anger (26): 5.2

There is a pretty strong effect in favor of anxiety over depression. There were not enough OCD, panic, or anger patients to get a clear picture of where those fell in relation to the other two. As far as I know this is the first study to back this claim up. But since I didn’t directly ask about dose, we can’t rule out that doctors give higher doses for anxiety and higher doses work better.

4. How many people experience side effects on SSRIs?

70% of people taking the drugs had at least one of the side effects on the list below:

(on this list, mild is exclusive of severe. So for example if 10% of people had mild side effects and 5% of people had severe side effects, a total of 15% of people had at least mild side effects)

SEXUAL DIFFICULTIES:
Severe: 11%
Mild: 41%
None: 48%

EMOTIONAL BLUNTING:
Severe: 8%
Mild: 31%
None: 61%

FATIGUE:
Severe: 6%
Mild: 18%
None: 76%

COGNITIVE DIFFICULTIES:
Severe: 3%
Mild: 16%
None: 81%

MADE DEPRESSION WORSE:
Severe: 2%
Mild: 5%
None: 93%

The more recently someone took the SSRI, the more side effects they were likely to have. While I can imagine innocent explanations for this, the most likely is recall bias: after a while, people forgot about some side effects. The real numbers are probably a little higher than this.

Most people’s side effects went away quickly after stopping the SSRI, but 15% of people who stopped the medication more than five years ago said their side effects never went away. Although post-SSRI-sexual-dysfunction is sort of known to the psychiatric consensus, this is a shockingly high number, which doesn’t seem consistent to me with how little you hear about this; I’m not sure what to think. The survey wasn’t really designed to ask which side effects these were, but just eyeballing the individual entries it looks like mostly sexual, with a small amount of emotional thrown in. But these are just the two most common side effects, so it doesn’t necessarily mean these two are more persistent than others.

5. Do some SSRIs produce worse side effects than others?

I think the psychiatric consensus on this question is that Paxil has worse side effects than the others, which are all equal.

This survey failed to directly replicate that. Four of the five side effects elicited (sexual difficulties, fatigue, emotional blunting, cognitive problems) were the same across all drugs. The only one that differed was worsened depression, which was slightly less common on Zoloft. This was technically significant but given the number of tests I would not put too much stock in this.

I forgot to ask about a few important side effects, including weight gain. I suspect that Paxil scored worst on the “overall” category because it produced worse side effects in the categories I forgot to ask about, or because people remembered it had side effects but couldn’t remember exactly what they were. Overall this survey doesn’t really make me doubt the consensus that it is probably worst.

6. How many people have trouble discontinuing SSRIs?

Good question! This has been a topic of interminable debate in the medical community, with some saying these problems are very common and others saying they are very rare. This survey found:

59% don’t remember having any issues at all
22% remember having a few minimal issues but not really thinking about them
14% remember having moderate issues that caused significant distress but were not disabling
5% remember having severe issues that seriously impacted quality of life

6. What factors made SSRI discontinuation easier or harder?

Hard to tell.

Everyone believes that a more gradual taper makes things easier, but the survey quite clearly found that people who reported longer tapers had worse problems. I’m pretty sure this is because if their doctor expected them to have problems (or they started it and did have problems) they put them on a longer taper. But this kind of thing makes it hard to make any real recommendations. However, people who came off their medication accidentally because they ran out did have by far the worst time, suggesting that cold turkey discontinuation really isn’t the way to go.

The longer a person had been on SSRIs, the harder their taper was likely to be. However, I’ve heard some people give overly dire warnings like “If you’re on these drugs for more than five years, don’t try coming off”. These were not justified. Even among people who were on the medication over five years, 49% tapered with “no issues”, and only 15% reported severe issues.

People with anxiety and OCD reported more difficult discontinuation than people with depression. This could be either because these conditions require higher doses, or because people with anxiety and OCD are more likely to notice and worry about minor symptoms.

Psychiatric consensus says that Paxil is the hardest SSRI to get off, and Prozac is the easiest. This survey confirmed that result. On a scale from 0 – 10, where 0 is the easiest discontinuation and 10 is the most difficult:

Paxil: 2.8
Lexapro: 2.7
Zoloft: 2.2
Celexa: 2.1
Prozac: 1.5

Prozac separated from Zoloft, Lexapro, and Paxil, but not from Celexa. The average person had only a 59% chance of having no discontinuation symptoms; the average person on Prozac had a 71% chance.

In any case, almost everybody’s taper was successful eventually. Only 0.5% of people said they gave up and stayed on the SSRI because they found discontinuation too difficult.

Summary

This survey had few surprises.

Already when giving someone an SSRI, I debate between Lexapro and Prozac. Lexapro is usually the most effective (by a tiny hair), but Prozac is the least likely to cause discontinuation syndrome. Although a natural strategy might be to taper Lexapro (or something else) very slowly in order to match Prozac’s slow half-life, studies show this doesn’t work (why not?), and this survey confirms it. There is no obvious right answer between these two as first-choice SSRI. This study does confirm my prejudice that giving Paxil is an obvious wrong answer and you should never do it outside specific rare circumstances.

The main surprise was the high number of people who claim their SSRI side effects never went away. Although this is a known very rare possibility, the survey suggested it was much less rare. One can imagine innocent ways this could happen: for example, someone goes on SSRIs for ten years, comes off, and is surprised to find their sex drive is lower than it was when they were a teenager ten years ago. This probably requires more careful and rigorous study than can be done in a silly online survey – and so will probably never happen.