Fluoxetine (Prozac)

What is fluoxetine (Prozac) used for?

Fluoxetine is a prescription-only antidepressant primarily used to treat major depressive disorder (MDD) in adults. It is also licensed for obsessive-compulsive disorder (OCD), bulimia nervosa, and, in some cases, panic disorder. It is commonly known by the brand name Prozac[1][2]. 

How does fluoxetine work?

Fluoxetine belongs to a class of medicines called selective serotonin reuptake inhibitors (SSRI) antidepressant. It works by increasing the level of serotonin in the brain, a chemical that helps regulate mood, sleep, and emotions, thereby improving symptoms of depression, anxiety, and other conditions. 

Who can take fluoxetine?

Most adults can take fluoxetine for depression, OCD, and bulimia. Children over 8 years old can take it for depression[1]. 

Fluoxetine may not be suitable for everyone, and you should always check with your doctor or pharmacist before taking it if you[2]: 

• Are allergic to fluoxetine or any of its ingredients. 

• Are pregnant, planning to become pregnant, or breastfeeding. 

• Have heart problems 

• Have glaucoma (increased pressure in the eye) 

• Always consult your doctor or pharmacist if you have liver problems, epilepsy, diabetes, or a history of bleeding disorders 

• Are taking or have recently taken monoamine oxidase inhibitors (MAOIs) 

• Have heart conditions, such as irregular heart rhythms 

• Have liver or kidney disease, epilepsy, diabetes, or a history of bleeding disorders 

Please tell your doctor or pharmacist about any conditions you may have before starting fluoxetine, and always follow the instructions in the Patient Information Leaflet[2]. 

What is the typical dosage of fluoxetine?

The initial adult starting dose of fluoxetine for depression is 20mg once daily. The dose can be increased gradually, depending on your response, to a maximum of 60mg daily. The initial dose for children is 10mg daily, but this can increase to 20mg daily under specialist supervision. Elderly patients or those with liver impairment may require lower doses. Always follow your doctor’s instructions[1]. 

How do you take fluoxetine?

Fluoxetine is taken once daily, best in the morning if you have trouble sleeping, although it can be taken any time of the day. It can be taken with or without food. Take fluoxetine at the same time each day to maintain consistent levels in your body[1]. 

Fluoxetine comes in the form of tablets, capsules, and liquid. You should swallow the tablets and capsules with a drink of water without breaking or crushing.  If you take the liquid form, it should come with a syringe or spoon designed to hold the correct amount. If you do not have either, ask your pharmacist rather than using a kitchen teaspoon[1]. 

Can you stop taking fluoxetine?

If you've been feeling better for 6 months or more, your doctor or pharmacist may suggest reducing your dose gradually over several weeks, or months if you've been taking fluoxetine for a long time. This is to help prevent you from getting any withdrawal symptoms as you stop taking the medicine[2]. 

Do not stop taking fluoxetine suddenly, or without talking to your doctor or pharmacist first. Stopping abruptly can cause withdrawal symptoms like feeling sick, dizziness, sleep problems, and irritability[2]. 

What do you do if you take too much fluoxetine?

Taking more than the prescribed dose can lead to symptoms like nausea and vomiting, confusion, or a fast/irregular heartbeat, agitation. If this happens, please contact 111 for advice or call 999 for emergency assistance[1]. 

If you need to go to A&E, do not drive – either get someone else to drive or call 999 and ask for an ambulance. Make sure you take the fluoxetine packet or leaflet, any remaining medicine, and any other medicines you take with you[1]. 

What do you do if you forget to take fluoxetine?

If you miss a dose, take it as soon as you remember. If it's almost time for your next dose, skip the missed dose and continue with your regular schedule. Never take 2 doses at the same time[1]. 

Medicines you can and can’t take with fluoxetine

Lots of medicines can affect fluoxetine, and it is important to tell your doctor or pharmacist about all medicines and supplements you are taking before starting the medication. 

Avoid combining fluoxetine with[1]: 

• Other antidepressants MAOIs, SSRI’s 

• Certain antipsychotics (e.g., thioridazine, pimozide) 

• St John’s Wort (herbal remedy) 

Take caution with[1]: 

• Blood thinners (e.g., warfarin) 

• NSAIDs (e.g., ibuprofen) 

• Triptans (for migraines) 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of fluoxetine?

The most common side effects of taking fluoxetine include[1]: 

• Nausea 

• Headache 

• Trouble sleeping 

• Fatigue 

• Diarrhoea 

• Serotonin syndrome (confusion, fever, muscle twitching) 

Some of the serious side effects (seek help, call 999 or go to A&E) include[1]: 

• Suicidal thoughts (especially in young people) 

• Seizures 

• Severe allergic reactions 

• Chest pain, or shortness of breath. 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice.

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about fluoxetine

How long does fluoxetine take to work? 

It may take up to 2 weeks to start feeling better, though some symptoms may improve sooner. It may take 4-6 weeks before feeling the full benefit[1]. 

Can I drink alcohol while taking fluoxetine? 

You are able to drink alcohol with fluoxetine, but it may increase side effects like drowsiness and impair judgment. It is best to avoid it initially in the early stages[1]. 

Is fluoxetine addictive? 

No, Fluoxetine is not addictive, but stopping suddenly can cause withdrawal symptoms[1]. 

Can I take fluoxetine during pregnancy? 

Fluoxetine can be taken during pregnancy. Speak to your doctor or pharmacist and they will help weigh up the risks and benefits so you can decide on the best treatment[1]. 

Will fluoxetine affect my sex life? 

Fluoxetine could improve your sex life as your mood lifts and you become more interested. However, it can also cause reduced sex drive, or some people could have difficulty achieving orgasm. Sexual side effects usually pass in a few weeks[1].  

Where can I get mental health support?  

If you have questions about fluoxetine or need mental health support, contact: 

- GP or pharmacist. 

- NHS 111 for non-emergency advice. 

- Mental health charities like Mind or Samaritans (call 116 123).  

Always seek help if you feel overwhelmed or experience worsening symptoms.

For the official NHS guide to fluoxetine, visit their website.