Skip to main content
Drug Info

Does Prozac make you tired?

It’s a potential side effect, though not everyone will experience fatigue
Heidi Borst
By | Jul. 30, 2024 Medically reviewed by Marissa Walsh, Pharm.D., BCPS-AQ ID
Pill wearing a sleep mask — Does prozac make you tired?

Key takeaways

  • Fatigue is a potential side effect of Prozac (fluoxetine), although not everyone will experience it.

  • Fatigue associated with Prozac is typically temporary and tends to improve over time. Implementing strategies such as maintaining a balanced diet, practicing good sleep hygiene, and moderating caffeine and alcohol intake can help manage Prozac-related fatigue.

  • If fatigue persists or becomes severe, it is recommended that you seek medical advice from your healthcare provider for further evaluation and guidance.

Prozac (fluoxetine) is a type of antidepressant called a selective serotonin reuptake inhibitor (SSRI). It is FDA approved to treat various mental health conditions, including major depressive disorder (MDD), obsessive-compulsive disorder (OCD), panic disorder, and eating disorders like bulimia nervosa. It may be used with Zyprexa (olanzapine) for treatment-resistant depression and episodes of depression in patients with bipolar disorder.

If you take fluoxetine for symptoms of depression, you may notice it changes how you feel. While many people feel less anxiety and improved mood on Prozac, it can also make you feel sleepy. Here’s what to expect when taking this prescription drug.

Does Prozac make you tired?

Sleepiness is a potential side effect of Prozac, according to Harold Hong, MD, a board-certified psychiatrist and Medical Director of New Waters Recovery in Raleigh, North Carolina. Not everyone who takes fluoxetine will experience tiredness. In fact, SSRIs are less likely to cause fatigue than older classes of antidepressants, such as tricyclic antidepressants and monoamine oxidase inhibitors (MAOIs).

Prozac can also have the opposite side effect: insomnia or difficulty sleeping, says Anandhi Narasimhan, MD, a board-certified child, adolescent, and adult psychiatrist in Los Angeles, California. In other words, Prozac can increase or decrease energy levels. If you do feel tired on Prozac, Dr. Narasimhan says how long it lasts is variable. If you find yourself sleeping a lot, you may be more sensitive to the potential sedative side effects of SSRI antidepressants like Prozac (fluoxetine), Zoloft (sertraline), Paxil (paroxetine), and Celexa (citalopram), she says.

According to Michael McDowell, DNP, a board-certified psychiatric nurse practitioner at Relief Mental Health, the most common side effects of fluoxetine are gastrointestinal. They include:

  • Diarrhea
  • Nausea
  • Indigestion
  • Constipation
  • Abdominal discomfort
  • Changes in appetite

Other potential side effects include:

  • Dizziness
  • Dry mouth
  • Headache
  • Insomnia
  • Tremors
  • Sweating
  • Yawning
  • Weight loss
  • Weight gain
  • Decreased sex drive
  • Ejaculation dysfunction

Additionally, there are rare but more serious side effects, such as:

  • Drug-induced movement problems (extrapyramidal effects)
  • Suicidal thoughts and behaviors
  • Increased heart rate, irregular heart rhythm, and heart problems
  • Changes in blood pressure
  • Seizures
  • Bleeding
  • Serotonin syndrome
  • Mania or hypomania
  • Low sodium
  • Low blood sugar
  • Angle-closure glaucoma
  • Pulmonary fibrosis
  • Prolonged and painful erections
  • Severe allergic reactions


Prozac use in individuals who are breastfeeding should be a shared decision between a healthcare provider and patient to consider the risk of infant exposure, the benefits of breastfeeding, and the benefits of treatment to the mother. It’s important to note that Prozac, as well as other SSRIs, has a black box warning—the FDA’s most serious warning for potential drug safety risks. This warning is due to an increased risk of suicidal thoughts and behaviors in young adults.


RELATED: How long does it take for Prozac to work?

Why does Prozac make you tired?

The mechanism by which Prozac induces fatigue is not fully understood. However, it is believed to be linked to the medication’s impact on serotonin levels in the brain. “Serotonin is a neurotransmitter that helps regulate mood, and alterations in its levels can affect energy levels and sleep patterns,” says Dr. Hong.

Studies have shown that fatigue is a relatively common side effect experienced by individuals initiating SSRIs. In one older study of 401 outpatients taking SSRIs, 17% experienced fatigue.

Prozac reaches its peak concentration in the bloodstream approximately 6 to 8 hours after administration. Due to its long half-life, Prozac’s effects can last for several days. Dr. Hong says the duration and intensity of fatigue can vary from person to person. Still, it is generally temporary and tends to improve over time, typically within four to six weeks. In most cases, Prozac fatigue will gradually diminish as your body adjusts to the medication.

RELATED: Zoloft vs. Prozac | Lexapro vs. Prozac

Managing Prozac fatigue

If you are experiencing fatigue from Prozac, Dr. Hong recommends implementing the following strategies:

  • Take Prozac at night (with your prescribing healthcare provider’s approval) if drowsiness is an issue during the day.
  • Maintain a regular sleep schedule.
  • Incorporate physical activity into your daily routine.
  • Stay hydrated and eat balanced meals.
  • Avoid caffeine and alcohol, which can affect sleep quality.
  • Maintain a healthy weight.

It may take a few weeks to adjust to Prozac’s side effects. Consult your healthcare provider if fatigue starts affecting daily function.

RELATED: What’s the best antidepressant for me?

When to see your healthcare provider

McDowell advises that if you experience severe or persistent fatigue while taking Prozac, you should consult a healthcare professional. They can assess your symptoms, monitor your response to the medication, and make any necessary adjustments to your treatment plan to ensure your well-being.