Do you suffer from hypothyroidism? If so depression, lack of energy as well as a million other side effects come with this disorder even when your medication is the right dose. I know from experience, I am constantly tired, and I am borderline anemic which again is cause by the thyroid disease so I have to take supplements every so often. The depression could be a side effect of the disorder..or not, it's hard to pin point. But anyone who constantly feels tired is most likely to feel more depressed. I wrestled with mild depression my teenage years which has only gotten worse since my thyroid disease was discovered. I try to avoid prescription anti depressants myself for the same reason...they make me more tired. I've been on the look out for a safe natural alternative for years, I've been taking st. johns wart for a few years, it helps a little but not much, I'm off it right now due to pregnancy. I've heard people using 5-HTP which I'm told is not the same as the once banned tryptophan in weight loss supplements. I haven't tried it, many people argue its safe and many argue its not.
Julie, maybe there's another reason that you feel tired all the time? Anaemia etc?See a qualified professional about your drug's effects. Support's on offer here, but online advice is not to be trusted.
If all other causes for your symptoms have been ruled out then you should look at depression as being your problem....but is tiredness your only symptom? This is a symptom of depression but normally there are others such as lack of motivation, sadness, feeling alone, sad and moody. If any medication makes you very tired, contact the prescribing doctor right away because it may not be the right medication for you. Unfortunately, finding the medication that works best for us is trial and error....but once we find the right one, it is well worth it. You may respond better to the Zoloft than you did the Prozac, you owe it to yourself to give it a try. But always work closely with your prescribing doctor on any side effects. Hope this helps and take care.