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Common side effects of Prozac

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About Prozac

Prozac® (generic name: fluoxetine) is prescribed as a treatment for people suffering from severe and chronic depression. It is one of a group of drugs called selective serotonin reuptake inhibitors (SSRIs) that also includes Lexapro (escitalopram), Celexa (citalopram), Paxil (paroxetine) and Zoloft / Lustral (sertraline).

Prozac is administered orally once each day. 

What is Prozac prescribed for?

Patients who have been diagnosed with one or more of the following conditions may be prescribed Prozac:

  • major depressive disorder (MDD)
  • obsessive-compulsive disorder (OCD)
  • bulimia nervosa
  • panic disorder
  • treatment-resistant depression
  • Bipolar I and bipolar II disorder, in combination with other medications.

What are the side effects of Prozac?

Prozac, as with most SSRI antidepressants, can cause some of the following mild side effects:

  • nausea
  • diarrhea
  • sweating
  • shaking
  • sexual problems
  • disturbing dreams
  • dry mouth and sore throat
  • insomnia
  • drowsiness
  • loss of appetite. 

Prozac is approved for use in children and adolescents but they may experience different side effects, including:

  • extreme thirst
  • heavier menstrual periods for girls
  • the need to urinate more frequently.

Less common and more severe side effects can include:

  • serious skin rashes
  • vasculitis (inflammation of small blood vessels)
  • increased blood pressure
  • seizures.

For the milder side effects, if they persist for more than a few weeks, or get worse, you should consult with your prescribing physician or a pharmacist. If you have severe side effects, go immediately to your doctor or local healthcare center.

One specific side effect that requires special attention is directly related to the nature of SSRIs. It is referred to as serotonin syndrome, and it is caused by excessive serotonin levels due to an overreaction to how SSRIs affect serotonin uptake. Too much serotonin can cause mild symptoms like diarrhea or shivering and more severe ones like muscle rigidity, fever and seizures. If untreated, severe serotonin syndrome can cause death.


How does Prozac work?

Serotonin is a neurotransmitter – one of the chemicals that are essential in transmitting signals inside the brain and along nerve paths to muscles and organs. The levels of serotonin regulate mood, sleep, appetite, and digestion. Low levels will aggravate any feelings of anxiety, anger and depression.

For people suffering from mood swings and depression, boosting serotonin levels can significantly reduce these feelings. 

Prozac affects the levels of neurotransmitters like serotonin. Serotonin is manufactured inside nerve cells, and is released to travel along nerve fibers and to nearby synapses, where they can pass the signal to adjacent nerves. In this sense, neurotransmitters can be thought of as the brain’s communication system. 

Nerves release serotonin in the brain. Some experts believe that an imbalance in levels of neurotransmitters is the cause of depression. 

Prozac works by preventing the reuptake of serotonin after it has been released by a nerve cell. Uptake works to remove released serotonin and restricting its action on adjacent nerves. Reducing uptake  increases free serotonin, which can then stimulate nerve cells.

For serotonin to effectively lower anxiety levels, SSRIs should be taken in daily doses for at least a couple of weeks. Its effect is to eventually cause changes in the structure of neurons and change the number of serotonin receptors throughout the brain. The higher serotonin levels boosted by SSRIs increase the brain’s capacity to restructure itself, making it more amenable to adaptation and remodeling.

This is why you are usually advised to stick to the prescribed dosage routines for at least a few months. You may not start to feel the benefits immediately. The best effects of Prozac will begin to kick in once the process of neuroplasticity has had an opportunity to work.

Recommended routines for Prozac – day or night?

Every person can respond differently to Prozac. There are no rules as to whether it’s better to take Prozac in the morning or at night-time. It’s mainly a question of your own reaction to the drug, especially the side effects it has on you. 

If the side effects are insomnia or restless sleep; urinary problems (mostly in young adults) or sexual problems like reduced libido or erectile dysfunction, then it’s generally better to take it in the morning.

If you experience common side effects like nausea, loss of appetite, headaches, diarrhea, feeling tired or weak, drowsy, unable to concentrate, then it may be better to take the dosage at night.

In the end, the decision to take it in the morning or evening will be one you should take, after consultation with your doctor, based mainly on your own experience with it.

What is essential is to be consistent with whichever routine you have decided on. Try to keep to the same time of day at which you take Prozac. If you miss a dose, try to make up for it within a few hours. Never double-dose. 

Improvements to your levels of anxiety and depression may take a few weeks. Stick to the plan even if you do not see the benefits immediately.

Does Prozac affect waking and sleeping routines?

The tiny pineal gland regulates the brain’s sleep-wake cycle (called the circadian rhythm), reacting to ambient light levels. It translates these signals and controls the production of melatonin, a hormone that induces sleepiness. It also controls levels of two other hormones – serotonin and dopamine. When light is brighter, it will produce more dopamine and reduce melatonin levels.

Dopamine keeps you awake. Drugs that increase dopamine levels, such as cocaine, nicotine, caffeine and amphetamines increase alertness. Serotonin has a more complex role in the circadian cycle. While it induces drowsiness, it can also stop you from falling asleep and cause restless and unsatisfactory sleep. 

What about Prozac and alcohol?

As a general rule, doctors will advise against drinking alcohol when taking medication. In the case of Prozac, there are specific reasons why you should not drink any alcohol when on Prozac.

Alcohol has some basic effects on your body that mimic Prozac. It is a depressant that slows down message traffic in the brain. Even in small quantities, it can cause problems like reduced power of judgment, fatigue, anxiety, impaired sight, or decreased motor skills. Prozac acts to slow down and reduce movement and alertness, just as alcohol does.

In combination, Prozac and alcohol can lead to sedation, even with one drink. This can lead to poor decision-making. It will almost certainly impair driving skills, and can increase the risk of falls.

In more extreme cases, alcohol and Prozac in combination can also lead to side effects like deeper bouts of depression and suicidal thoughts. On top of that, alcohol will also prevent Prozac from working correctly. You may not be getting the proper benefits of Prozac, and the symptoms can get even worse.

Is Prozac addictive?

Prozac is not addictive, but some patients may experience withdrawal reactions upon stopping treatment with Prozac too quickly. Sudden withdrawal can produce many side effects, including anxiety, nausea, nervousness, and insomnia. It should not be cut off suddenly, but instead the dose of Prozac should be gradually reduced when therapy is discontinued.

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