Does Prozac cause missed periods? (3 causes)

In this article, we will explore whether Prozac causes missed periods, how Prozac causes missed periods, the factors contributing to it and the steps to be taken in such a case. 

Does Prozac cause missed periods?

Yes, Prozac (Fluoxetine) can cause a missed period as a side effect. This may be because Prozac affects the hormonal changes that occur during the menstrual cycle. The changes it may cause include missed periods, irregular cycles or heavy bleeding. These can be due to:

  • Hormonal changes
  • Weight changes
  • Stress and anxiety

Prozac may not cause missed periods in every patient due to the individual variation mainly depending upon genetic variations.

If you miss your periods while taking Prozac, it is always advisable to consult your doctor for a better solution, identification and diagnosis.

How does Prozac cause missed periods?

The relationship between Prozac and missed periods is complex and is not yet fully understood. Prozac primarily acts on the central nervous system affecting serotonin levels in the brain (1). Prozac can cause a list of side effects such as nausea, vomiting, drowsiness, fatigue, headache etc.  Although the exact mechanism is not clear, there are many theories. Some are mentioned below.

Hormonal changes

Prozac can impact the delicate balance of hormones in the body, including those involved in the menstrual cycle (2). Alteration in the hormonal levels results especially by changes in serotonin. Modulations in serotonin levels can affect the hypothalamus, which plays a central role in regulating the menstrual cycle (3).

The hormones this may affect are pituitary hormones including luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin.

Weight fluctuation

Some individuals taking Prozac may observe changes in their weight and appetite, which can in turn affect the hormonal balance (4). Significant weight loss or weight gain can cause menstrual irregularities (5). The weight fluctuations cause fluctuations in the estrogen hormone that influence ovulation and the thickening of the uterine line (6). 

Stress and anxiety

Many individuals who are prescribed Prozac are suffering from depression, anxiety or some other mood disorder which can independently contribute to changes in the regularity of the menstrual cycle. Stress and mood disorders can disrupt cortisol levels by elevating them (7).

Elevated cortisol levels can have a suppressive effect on the hypothalamus-pituitary ovarian (HPO) axis, responsible for the menstrual cycle. 

Prozac and missed periods: research findings

The research conducted by Faruk Uguz in 2012 included 1432 women to determine the incidence of menstrual irregularities due to antidepressants. The study concluded that women taking antidepressants showed a higher rate of menstrual irregularities as compared to the control group (8).

Another study in 2012 investigated the effects of fluoxetine on the menstrual cycles of women. This study concluded that the incidence of menstrual irregularity is higher in women taking Prozac (fluoxetine) as compared to others (9). 

Significant research data is available that shows the effects of antidepressants particularly SSRIs on the menstrual cycle in women. 

What other factors may lead to missed periods while taking Prozac?

Several factors may lead to missed periods in the context of Prozac. These may include:

Higher dose: The dose of Prozac may play a role in determining the likelihood of experiencing menstrual irregularities. Higher doses might be associated with an elevated risk although this can vary among individuals (8).

Individual variation: Individual response to medications like Prozac may vary from individual to individual significantly. Some patients may be more susceptible to experiencing these side effects as compared to others (10). 

Duration of use: The length of time a person has been using Prozac may influence the likelihood of experiencing menstrual changes. Some individuals may notice alterations in their menstrual only after long-term use.  

Preexisting conditions: Underlying health conditions such as polycystic ovarian syndrome (PCOS), thyroid disorders or hormonal imbalances can significantly impact the menstrual cycle. These conditions may interact with the effects of Prozac potentially exacerbating menstrual irregularities. 

Can Prozac interact with other medications?

Understanding the interactions between Prozac and other medications is important to avoid the adverse effects. Prozac may interact with the following medications and lead to menstrual irregularities.

  • NSAIDs like ibuprofen and aspirin
  • Anticoagulants such as Warfarin
  • Anticonvulsants
  • Herbal Supplements including St. John’s Worts
  • Hormonal contraceptives
  • Dietary supplements such as vitamin E

It is essential to note that these interactions and menstrual irregularities are not universal experiences for individuals taking Prozac. Individual responses may differ based on various factors. In any case of such interactions or side effects, open communication with the healthcare provider is crucial. 

What to do if you miss your period while taking Prozac?

If you miss your period while taking Prozac then here are some things you can do:

Consult your healthcare provider: If you miss your period or experience significant changes in your menstrual cycle while taking Prozac, consult your doctor preferably a gynaecologist. Your doctor can assess your specific situation, conduct a thorough evaluation and determine whether the missed period is due to the medication or some other cause.

Rule out other causes: A physical examination to rule out the conditions of pregnancy, thyroid disorders, PCOS or other hormonal imbalances is important. Addressing these issues is essential for your health.

If there is a possibility of pregnancy, consider taking a pregnancy test to rule out this potential cause of missed period.

Adjusting Medication: If after a careful evaluation, Prozac is found to be the cause of missed periods, then reducing the dose of Prozac or altering the medication might be recommended. Alternatives to Prozac include

  • Other SSRIs such as Sertraline, escitalopram
  • SNRIs
  • Atypical antidepressant
  • Benzodiazepines
  • Tricyclic antidepressants

Lifestyle factors and stress management: Adopting a balanced lifestyle with a nutritious diet, regular exercise and stress management techniques can support hormonal balance and regulate the menstrual cycle. These factors play a significant role in menstrual regularity.

Healthy habits can help with a healthy menstrual cycle. The following are key points for a healthy lifestyle.

  • Management of weight
  • Management of the sleep cycle
  • Management of stress
  • Management of diet


In my opinion, Prozac may lead to a missed period. However, it is not a commonly reported side effect. Hence, other factors such as underlying diseases or disorders and pregnancy should be considered.  


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Domingues, R. R., Wiltbank, M. C., & Hernandez, L. L. (2023). The antidepressant fluoxetine (Prozac®) modulates estrogen signaling in the uterus and alters estrous cycles in mice. Molecular and cellular endocrinology, 559, 111783.



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Ko, K. M., Han, K., Chung, Y. J., Yoon, K. H., Park, Y. G., & Lee, S. H. (2017). Association between Body Weight Changes and Menstrual Irregularity: The Korea National Health and Nutrition Examination Survey 2010 to 2012. Endocrinology and metabolism (Seoul, Korea), 32(2), 248–256.


Reed, B. G. (2018, August 5). The Normal Menstrual Cycle and the Control of Ovulation. Endotext – NCBI Bookshelf.


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Steiner M, Lamont J, Steinberg S, Stewart D, Reid R, Streiner D. Effect of fluoxetine on menstrual cycle length in women with premenstrual dysphoria. Obstet Gynecol. 1997 Oct;90(4 Pt 1):590-5. doi: 10.1016/s0029-7844(97)00307-4. PMID: 9380321.


Amirkhani, Z. (2012, September 14). Relation between Fluoxetine and Menstrual Cycle Disorders.


Uguz F, Sahingoz M, Kose SA, Ozbebit O, Sengul C, Selvi Y, Sengul CB, Ayhan MG, Dagistanli A, Askin R. Antidepressants and menstruation disorders in women: a cross-sectional study in three centers. Gen Hosp Psychiatry. 2012 Sep-Oct;34(5):529-33. doi: 10.1016/j.genhosppsych.2012.03.014. Epub 2012 Apr 24. PMID: 22534402.

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