Prozac vs. Paxil? All you need to know about SSRIs

Have you ever wondered why you or others receive different antidepressant medications? Depression affects people in unique ways—it’s rarely the same across individuals. Some of us might feel more fatigue and low energy, others might be having difficulty falling asleep. Because our bodies are distinct, so too is our treatment.

So what are Paxil (Paroxetine) and Prozac (Fluoxetine)? If you've ever looked into antidepressants, you might have come across both of these prescription medications. Paxil and Prozac are both selective serotonin reuptake inhibitors (SSRIs). In this post, we'll explore their similarities, differences, possible side effects, and proper usage.

What are SSRIs?

SSRIs are antidepressants that treat both anxiety and depression by increasing serotonin levels in your brain. Serotonin is one type of chemical known as a "neurotransmitter" that transmits messages along certain pathways in the brain. It is a “feel-good chemical” that contributes to our feelings of well-being as well as having many other effects on our mood, appetite, and sleep-wake cycle.

Because SSRIs increase the levels of serotonin in the brain, it allows the brain to transmit messages related to feeling good more easily. The effects are improved energy, a more positive mood, and less depressed thinking patterns. SSRIs may take a few weeks to take full effect.

How are Prozac and Paxil different?

Both SSRIs have shown comparable success in treating depression, though Paxil has a higher response rate and takes effect sooner than Prozac. The greatest differences between the two SSRIs are in how each one is used and what the side effects are.

In addition to depression, Paxil is FDA approved to treat anxiety disorders (both social anxiety disorder and generalized anxiety disorder) and post-traumatic stress disorder (PTSD). Prozac is approved for depression, obsessive-compulsive disorder, and panic disorder, and is used off-label to treat anxiety and PTSD. Prozac is also sometimes used to treat bulimia.

What are the advantages of Prozac over Paxil?

Prozac is FDA approved for children eight or older. It also has a weaker potency as a serotonin inhibitor, which means it has less noticeable symptoms upon discontinuation than Paxil and many other antidepressants.

One of the major upsides of Prozac is that it seems to work better for patients with fatigue or low energy since it has a greater energizing effect than other antidepressants. However, this might not be a great option for those who have sleep difficulties. Make sure to let your provider know if you often feel fatigued or low energy when deciding a course of treatment.

What are the advantages of Paxil over Prozac?

Paxil is available for those who are 18 and up. It's one of the more potent SSRIs and doesn't have as many stimulating effects as some other medication, which means it can be taken at bedtime.

For those with a combination of depression, insomnia, and hyperarousal symptoms, Paxil may work better than Prozac. If you find yourself with this combination of symptoms, it may be worthwhile to bring it up with your provider for treatment.

What are the side effects of these medications?

In addition to the side effects previously mentioned, long-term SSRI use may lead to various side effects including weight fluctuations, sexual dysfunction, and nausea.

With Paxil, side effects may include constipation, indigestion, tremor, sweating, and muscle pain. As Prozac is a more stimulating antidepressant, it is more likely to cause insomnia and usually taken in the morning or afternoon rather than at night. Prozac may lead to greater nervousness and weight loss. Paxil, on the other hand, is more likely to cause weight gain. These are the common side effects, though not a comprehensive list.

What are the drug warnings of Paxil and Prozac?

If an individual is suicidal to begin with, he or she may be at a greater risk of suicide before the SSRI takes full effect. The reason is that SSRIs often improve energy first and then take a little longer to lessen depressed mood and thinking. When a person’s depression starts to lift and energy starts to return, he or she may feel less hopeless and helpless but still feel depressed. This doesn't necessarily mean that the medicine is making someone want to harm him/herself. Those who are already thinking of harming themselves may think about suicide as a way out, whereas before they were too immobilized to make a specific plan.

As such, their usage needs to be monitored. Taking either drug may trigger manic episodes for those with bipolar disorder and withdrawal symptoms if not discontinued properly.

Pregnant women should not use Paxil and only use Prozac if the benefits outweigh the risks. Both antidepressants should not be used with alcohol since it can increase drowsiness or dizziness.

What are the drug interactions of Paxil and Prozac?

When taking either antidepressant, it's important to be cautious of drug interactions. Both interact with monoamine oxidase inhibitors (MAOIs) such as selegiline and phenelzine. MAOI use must be discontinued 14 days before starting an SSRI.

The consequences of taking these together may increase the risk of serotonin syndrome, which may cause fever, agitation, and diarrhea. It is also recommended that Prozac and Paxil are taken independent of pimozide or thioridazine--taking them together may lead to an increased risk of QT prolongation or abnormal heart rhythm.

Prozac and Paxil may also interact with benzodiazepines, anticonvulsants, opioids, NSAIDs, and other blood thinners. Please note that this list is not comprehensive.

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We hope this guide provides some insight into the similarities and differences between Paxil and Prozac. Ultimately, it is important to consult your prescribing provider to find the medication that best suits your needs and medical history.

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