Can Prozac make you tired?

Can Prozac make you tired?

Prozac (Fluoxetine) can make you feel tired, especially during the early course of your treatment with this antidepressant. This is, in fact, one of the most common side effects of this medication. 

The intensity of tiredness caused by Prozac varies from person to person and it is considered dose-dependent. However, Prozac can also increase energy levels in some people and can cause insomnia and related sleep disturbances. 

What does research suggest?

There are several research studies on Prozac and how it affects energy levels. One study indicated that tiredness is one of the most common side effects of Prozac experienced during the first 2-3 weeks of the treatment, but it does start to get better.

Although it is a known fact that Prozac and other antidepressants can cause tiredness during the early course of the treatment, this antidepressant is believed to increase energy levels in the long run. 

A randomised, double-blind, placebo-controlled study indicated that Prozac can actually help manage the symptoms associated with chronic fatigue syndrome, once it kicks in (1). The study also added that Prozac can counteract lethargy by increasing your energy levels and motivation. 

Another research study published in the Journal of Clinical Psychopharmacology indicated that Prozac caused increased energy levels in depressed patients as compared to the placebo, and the energy levels increased further as the drug continued to treat depression (2).

One research study focused on sleep disturbances caused by Prozac, especially in people new to this antidepressant. The study concluded that Prozac may cause tiredness by affecting a healthy sleep cycle (3).

Should you be concerned about Prozac-induced tiredness?

You shouldn’t worry about Prozac-induced tiredness if you are new to this medication, or antidepressants in general. 

This is considered a common side effect and will most likely begin to fade away as your body adjusts to the medication. 

What to do if Prozac makes you tired?

It is best to reach out to your healthcare provider if you continue to feel tired and exhausted on Prozac. Although the side effect goes away within a few weeks, it might linger in some cases. 

Prozac is a good antidepressant, but it might not be the best antidepressant for you if it continues to affect your health. In the majority of cases, dose reduction works to reduce the side effects of Prozac.

Prozac can be taken at any time of the day, but your doctor may also ask you to take your Prozac at nighttime to help overcome the tiredness caused by this antidepressant. 

However, if the tiredness persists, your doctor might switch you to another antidepressant. Make sure you don’t stop taking Prozac without your doctor’s approval.

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Vercoulen JH, Swanink CM, Zitman FG, Vreden SG, Hoofs MP, Fennis JF, Galama JM, van der Meer JW, Bleijenberg G. Randomised, double-blind, placebo-controlled study of fluoxetine in chronic fatigue syndrome. Lancet. 1996 Mar 30;347(9005):858-61. doi: 10.1016/s0140-6736(96)91345-8. PMID: 8622391. Available from:


Judge R, Plewes JM, Kumar V, Koke SC, Kopp JB. Changes in energy during treatment of depression: an analysis of fluoxetine in double-blind, placebo-controlled trials. J Clin Psychopharmacol. 2000 Dec;20(6):666-72. doi: 10.1097/00004714-200012000-00013. PMID: 11106139. Available from:


Dorsey CM, Lukas SE, Cunningham SL. Fluoxetine-induced sleep disturbance in depressed patients. Neuropsychopharmacology. 1996 Jun;14(6):437-42. doi: 10.1016/0893-133X(95)00148-7. PMID: 8726754. Available from:

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