How do M.D.'s know which anti-depressant to prescribe?

I went to my general physician recently, and he suggested an anti-depressant for me, telling me that it really doesn’t matter which I take, since a recent JAMA or NEJoM article confirms that all SSRI’s are basically the same, or at least equal effective.

Without disputing his point, what process goes into choosing Prozac or Zoloft or Nardil or Calexa or Paxil? Is it mainly trial and error, or can M.D.'s specifically tell which Rx will work best for each patient? In short, how do they know which one to prescribe?

Can anyone recommend a good online guide on this–one that does not cost anything?

They may work roughly the same way, but each has slightly different primary effects and side-effects. Paxil, for instance, is very effective in treating accute panic disorder and anxiety disorders as well as depression. The other SSRI’s are not commonly used in this way.

Zoloft is very similar to Prozac in most aspects but has fewer side effects in most patients so it has become more popular than Prozac.

Your physician is probably right that the SSRI’s are pretty equal when it comes to treating depression. The main issue left is side-effects.

Just go to Google and type in “Zoloft side-effects”, then “prozac side-effects” and you should come up with plenty of material on why one is more suited to a patient than others.

The doctor interviews you to get to the root of your specific problem. Zoloft also gets perscribed for specific disorders that Prozac does not. I originally tried Zoloft, and did not like the side effects (groggy and buzzed). So I went to Prozac (jumpy and buzzed). The side effects go away.

Each body is different, so it would not be rare for someone else to have the opposite side effects. Actually, it is not certain how anti-depressants really work. The seratonin uptake stuff is just a good hypothesis. So the doctor will perscribe a drug, set another appointment in a month to see how you feel. If you are better, continue the dosage. If not, increase dosage or try something else.

There’s also more than one kind of anti-depressant. In addition to the SSRIs, there are tricyclic anti-depressants, and miscellaneous anti-depressants.

For example, I can’t take any of the SSRIs, because I’m bipolar and they trigger manic episodes. So, my doctor and I kind of played trial-and-error before we found stuff that actually worked. Also, some meds have side effects that make them desirable for certain kinds of depression. For example, I take Serzone because it causes drowsiness. This is a good thing when you have anxiety, as I do. Trazodone, in some doses, is used as a sleeping pill.

A lot of it comes from the doctor’s own experience with these meds. You might also request a consultation with a psychiatrist to fine-tune any meds you might need.

(IANAD, BTW. I’ve just been on and off meds for quite a while.)


It’s mainly trial and error. And yes, the side-effects are one of the primary issues; although certain medications are more effective in some people than in others, there aren’t any that are generally more effective over the population as a whole.

IANAD, just a patient. And
TMI Alert!!
I had been on Luvox for depression, and the main side effect for me was difficulty in reaching sexual climax. This didn’t bother me at first (I can bang away all night, baby! Ever had multiple orgasms? :wink: ), but it definitely got old after awhile. Now I’m taking Wellbutrin-had insomnia for awhile after I first started taking it, but that issue faded & it’s working well for me.

As others have pointed out, side effects are a major consideration when selecting an antidepressant. One problem with internists who prescribe them is that they often tend to stick with the one they know best or the one that works for them personally. That’s OK if it works for you but, if their first choice doesn’t do the trick, they are often at a loss how to proceed.

An internist, for example, would be very unlikely to prescribe Nardil because it requires the patient to cooperate reliably with dietary restrictions to prevent dangerous, hypertensive reactions. They will stick with the relatively benign SSRI’s, as a rule. If you have serious depression which does not respond to an SSRI, you need a psychiatrist. Many patients require more than one medication after all the trial and error. Again, this is most likely to be figured out by a specialist.

One more note of interest. If you inherited your depression from, say, your mother; find out which antidepressant worked for her. That would be the most likely med to work for you too and would be the best place to start.

Of course, I should point out here that the MULTI-BILLION dollar ad campaigns that the pharmaceutical manufacturers run have absolutely NO EFFECT on the way medications are chosen. Most of the medical journals have expensive full-page or fold-out, full-color ads touting specific medications- not that this could EVER influence doctors, because only us ‘ignorant’ folks are persuaded by advertising.

Drug companies also bombard doctors’ offices with free samples, pens, letter-openers, calendars, and all sorts of knick-knacks, do-dads, and jim-cracks that are plastered with the names of certains medications. Remember, this has NO EFFECT whatsoever on how doctors prescribe medications!

One nice thing though, about the free samples is that when my family was between insurance companies, my psychiatrist was able to give us some free samples of Paxil-which I’m on for Obsessive-Compulsive-Disorder.

The worst side effect was it made me groggy, so I’d take it in the morning, be sleepy and wide awake before bedtime. That was solved by taking it at 9 pm every night. It eventually wore off, or I don’t notice it, but I still take it at night.

Zoloft, Prozac and Paxil are all SSRIs and probably more similar than drug literature would have us believe. Paxil is the only one currently approved for treatment of social anxiety and is useful for depression with an element of anxiety. It also tends to make patients drowsy and can be useful if sleep is impaired. It causes lots of side effects, though, especially for the first couple weeks; mainly gastrointestinal and a drugged-drowsy sensation. Zoloft has fewer side effects and I tend to use it in more elderly patients. In this population, depression is often subtle and it is important to ask specifically about hobbies and activities. Prozac is cheap (generic), dependable and a good choice too. Celexa is newer and supposedly more specific for serotonin (versus dopamine or norepinephrine).

All of the SSRIs can have side effects including change in weight, anxiety, anorgasmia or ejaculation difficulties, insomnia and gastrointestinal stuff.

There are other classes. SNRIs inhibit both uptake of serotonin and norepinephrine. Hence, Effexor is now being used more commonly. Serzone is similar to the SSRIs but as a 5-HT2 inhibitor it is said to have a low rate of sexual dysfunction. Wllbutrin is an aminoketone unrelated to other classes chemically - it helps smokers and can cause seizures but no one knows how it works. Tricyclic antidepressants such as Elavil (amitryptiline) are excellent for neuropathic pain and as effective as SSRIs, but they have more side effects and overdoses can be very serious. Modified cyclics like Remeron and Trazadone are being used more commonly. I think few doctors would choose Nardil, these days, since the old MAO Inhibitors have a lot of side effects especially if taken with certain foods, cold remedies or Demerol. Moclobemide (Manerix) seems to lack these side effects and is a “selective” MAO-A inhibitor.

Theoretically, one could classify symptoms in a Venn diagram on the dopamine, norepinephrine and serotonin “symptoms” and pick the best one. In practice, this doesn’t work out wonderfully and trial and error is involved, but most doctors would ask:

  • Am I treating depression? Do I have a good diagnosis? Does this require medication or would lifestyle adjustments and/or counselling suffice?

  • Is there coexisting mania, hypomania, anxiety, neuropathic pain or personality disorder? Is there reasonable risk of overdose? Is there an “addictive personality” on a substance use history?

  • Would there be benefit from sedation? Which side effects does th epatient consider unacceptable?

  • Would this patient prefer to try a less expensive antidepressant given several might be equally effective?

  • How old is the patient? Do they have other health problems which would preclude the use of certain drugs? Do they have livers and kidneys which work well? Are they taking other medicines which might interfere with a possible choice?

This question has alot of answers. GP’s are generally vastly uninformed vs. the average psychopharmacologist. And among gp’s there is a huge disparity because some maybe particularly interested in anti-depressants vs. others. In the initial choice between say, Prozac and Zoloft, I would guess virtually 90% is doctor’s influence by marketing and peer’s vs. documented evidence of anykind. If one doesn’t work, they try another.
There are also mood stabilizers such as lithium, depakote, neurontin, and lamictal for bipolar disorders. Typically people start with depakote then neurontin then lamictal (if the doctor is particulary well informed) and then lithium as last resort.

Dr_Paprika, thank you for the clarification.

I find it interesting after reading all of that, that my GI proscribed Paxil for me during an acute Chrons flare up. You’d think that a med with less gastrointestinal effects would be the choice. Go figure. :wink:

I only took the Paxil for a few days, then quit, as one of the side effects were these unpleasant electrical tingley (thru the large muscle areas (arms, legs)) sensations.

As a family doctor, I prescribe a fair number of anti-depressants. Like most GPs, I keep up to date on the literature. And having worked closely with a few psychopharmacologists, I guarantee that they also use some trial and error. You can try to match specific symptoms of depression and anxiety to dopamine/NE/serotonin, but clinically the results differ from the academic prediction.

The local psychopharmacologist here likes mixing Remeron and Effexor for difficult cases; he also does ECT on very difficult cases. There is an enormous disparity among antidepressant use among psychopharmacologists who also are influenced by drug companies. If you bad-mouth GPs again I’m going to give you some Nasonex then knock the snot out of you.


I have also found many insurances dictate what you take. For instance at work last year the insurance stopped covering Prozac and made everyone switch to Paxil.

I’m sure once Prozac is generic (or is it already) that will change back.

I have taken Prozac for anxiety attacks. Didn’t help at all. Paxil helped within 1 day. No Side effects at all.

I find the people I talk to about drugs that have side effects all without exception have looked in med books and the internet on what they could have for side effects. Those without them all but two didn’t.

That obviously isn’t scientific but the internet tends to be one horror story after another about drugs.

how is one diagnosed as being bipolar?

Is it general proven knowledge that if you are bipolar, you can not take SSRI’s? For example, I have seen everywhere if you are taking MAOI’s, you are strictly forbidden other meds, is the same true for bipolar people?

There is a wide range in the bipolar spectrum. Those who are not prone to manic or hypomanic episodes usually tolerate SSRI’s OK. Sometimes I get the feeling that the bipolar diagnosis is inappropriately applied. It seems that every patient I see these days who has ever been depressed, has been diagnosed bipolar by somebody.