Does Prozac Make You Tired? How Long It Lasts and What Helps
Prozac can make you tired or sleepy, even though it keeps others awake, and for many people it eases.
By withClaro Editorial · 2026-11-02 · 4 min read
Clinical section reviewed by Dr. Jason Tan , Consultant Psychiatrist, on October 27, 2026.
Key takeaways Prozac can make you tired: in the FDA depression trials, 13% felt sleepy and 9% felt weak or low on energy, against 6% and 5% on placebo. Of 100 people on r/prozac who said how their tiredness went, 48 said it faded and 52 were still tired when they wrote. People most often said an evening dose helped. Tell your prescriber if tiredness lasts beyond the first weeks or comes with low motivation. On this page
How tiredness on Prozac went for people on r/prozac How common is tiredness on Prozac? Why does Prozac make me tired if it's supposed to be energizing? How long does tiredness from Prozac last? What helps with tiredness on Prozac? Is it safe to drive if Prozac makes you sleepy? What should you tell your prescriber about tiredness? Prozac (fluoxetine) can make you tired, even though it keeps other people awake. Sleepiness and low energy are both on the FDA label's list of common side effects. For many people tiredness eases as the body adjusts, and the time of the dose can help.
How tiredness on Prozac went for people on r/prozac
Of 100 people on r/prozac who said how their tiredness went over time, 48 said it faded while they stayed on Prozac and 52 were still tired when they wrote. We read 100 recent threads about tiredness and energy, comments included, and 238 people described their own experience; 223 of them said Prozac left them tired, sleepy or low on energy. These threads were picked because people posted about tiredness, so they show what it looks like when it happens, not how often.
Of all 223 who were tired, 23 said taking the dose in the evening helped, and 10 said it eased with time.
One person on r/prozac wrote:
I had fatigue for two months, hang in there. It’ll pass
For another it had not lifted:
since august I have just been so... TIRED
How common is tiredness on Prozac?
In the label's depression trials, 13% of people on Prozac had somnolence, meaning sleepiness, against 6% on placebo. Another 9% had asthenia, meaning weakness or no energy, against 5%. The label lists these as two separate effects: one is wanting to sleep, the other is running out of strength while awake.
Why does Prozac make me tired if it's supposed to be energizing?
Because the same medicine affects people differently. Prozac has a reputation as one of the more energizing SSRIs, but in the same trials sleepiness and insomnia were both more common than on placebo: 13% against 6%, and 16% against 9%. There is no way to know in advance which you will get, and some people get poor sleep at night and sleepiness in the day.
How long does tiredness from Prozac last?
The NHS says some side effects ease after a couple of weeks, but some can last longer. On r/prozac, about half of those who said how it went said it faded; one person wrote that their fatigue lasted two months. Fluoxetine builds up over 4 to 5 weeks, so tiredness can appear or change during that time, and after a dose increase. When the mood benefit usually arrives is covered in how long Prozac takes to work .
What helps with tiredness on Prozac? Medically reviewed by Dr. Jason Tan on October 27, 2026, this section only.
Moving the dose to the evening is the first thing many people try, and 23 people on r/prozac said it helped. With daily use, fluoxetine levels change little across the day, so the label gives no clear reason it should work, and it gives Prozac in the morning. Decide on a change with your prescriber. The clinical view:
Tiredness is common in the first weeks of an antidepressant and often eases as your body adjusts.
When it lasts, it can come from the medication, from depression itself or from poor sleep.
What can help:
taking the dose in the evening, if your medication allows it regular sleep, daylight and light activity, rather than extra caffeine not driving or using machinery if you feel drowsy Tell your prescriber if tiredness lasts beyond the first weeks or comes with low motivation and feeling flat. A lower dose or a different medication can help. How to move your dose time is covered in the best time to take Prozac .
Is it safe to drive if Prozac makes you sleepy?
Not while you feel sleepy. The NHS says not to drive, ride a bike or use machinery if fluoxetine makes you dizzy or sleepy. Alcohol can add to the drowsiness.
What should you tell your prescriber about tiredness?
Tell your prescriber when the tiredness started, how strong it is and whether it is getting better. It helps to tell them:
When you started Prozac, your dose and any recent dose change. When in the day you feel tired, and when you take your dose. How you sleep at night, and whether you nap. Whether you also feel flat, unmotivated or low. Any other medications, caffeine or alcohol you use. Some tiredness is not a side effect. If it comes with losing interest in things, feeling flat and a low mood that is getting worse, it may be the depression itself, and that is worth raising before the next visit. New thoughts of suicide or self-harm, especially in the first weeks, need a call to your prescriber the same day. If you're having thoughts of harming yourself, contact emergency services or a crisis line straight away. In the US, call or text 988. In the UK, call Samaritans on 116 123. Elsewhere, find a crisis line near you .
Download on the App Store Tiredness on Prozac rises and fades over weeks, so a day-to-day record shows the pattern better than memory. The withClaro app lets you log energy, sleep, mood and side effects each day, linked to your dose, and turns it into a report for your prescriber.
Frequently asked questions Does a higher dose of Prozac make you more tired? It can for some people. Tiredness can appear or get stronger after a dose increase. Tell your prescriber when it started.
Can tiredness on Prozac be a sign of low sodium? Rarely. The label warns that SSRIs can lower sodium, and the signs include weakness, headache, trouble concentrating, confusion and unsteadiness. Older adults and people on water pills are more at risk. If weakness comes with confusion or unsteadiness, call your prescriber.
Is Prozac or Zoloft more likely to make you tired? Both can. Each label lists sleepiness among common side effects at a similar level, but Prozac's figure comes from depression trials and Zoloft's from trials across six conditions pooled, so the labels can't tell you which one you will tolerate better. Raise tiredness when your prescriber chooses a medication.
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Sources PROZAC (fluoxetine) prescribing information, US Food and Drug Administration via DailyMed NHS: Fluoxetine ZOLOFT (sertraline) prescribing information, US Food and Drug Administration via DailyMed, revised August 2023 Claro articles are for self-monitoring and educational purposes only. They are not a medical device, therapist, or diagnostic tool, and do not replace care from your prescribing clinician. If you are in crisis, contact your care team, emergency services, the Samaritans (UK: 116 123), or the Crisis Text Line (US: text HOME to 741741).