Paxil (Paroxetine) is a drug that has been approved since 1992 for the treatment of major depression. It is considered by many to be a highly effective medication for various types of anxiety, specifically: generalized anxiety disorder, social phobia, OCD, and panic disorder. Paxil functions as an SSRI (selective serotonin reuptake inhibitor) and is considered to be one of the most potent drugs in this particular class.

While many people find that Paxil works well to treat their anxiety and depression, like all drugs it carries side effects. Some of these side effects may be minor, but others may actually make it difficult to justify continuing treatment with this particular medication. Despite the fact that this drug may effectively treat an array of psychiatric conditions, some people avoid Paxil for the fact that it is one of the most likely SSRIs to cause weight gain.

Paxil and Weight Gain

Nearly everyone taking Paxil is at risk for weight gain. While not everyone taking Paxil is necessarily guaranteed to gain weight, those taking moderate to high doses of the drug will likely pack on a few pounds. A majority of people speculate that the drug alters the body’s baseline metabolism, and slows it to a significant extent. Others believe that the drug may cause increased cravings for unhealthy foods like simple carbohydrates.

How Paxil Causes Weight Gain: List of Ideas

There are a variety of ways in which Paxil may be contributing to weight gain. Some experts believe it causes the metabolism to slow, while others believe there is a link between serotonin changes and food cravings. I’m of the mindset that it’s likely a combination of factors that vary based on the individual.

  • Appetite boost: Many people who take Paxil notice a change in appetite. Prior to taking the medication, a person may have lost weight or remained a low weight because they weren’t eating enough while depressed. When the drug works, some people feel better again and start taking better care of themselves, which can lead to eating adequate sized meals. Additionally some people notice that the drug gives them a significant uncontrollable appetite boost, leading them to eat more than usual.
  • Carbohydrate cravings: Some have claimed that Paxil has made them more inclined to seek out unhealthy foods like refined sugars, processed foods, and carbohydrates. There is a clear link between carbohydrates and the serotonin system, but it is unknown specifically how it is influenced by Paxil on an individual basis. If you experience food cravings that you didn’t previously have, it could be a result of the Paxil.
  • Drug interactions: There are notable examples of drugs that interact with Paxil to markedly amplify weight gain. An example would be taking Paxil and Risperdone (an antipsychotic) together. These two medications have been found to lead an individual to gain nearly 30 pounds in just 5 months of treatment. Researchers believe it is a result of a drug-interaction that inhibits the CYP4502D6 enzyme.
  • Fat storage: The changes induced to a person’s physiology from the drug Paxil could account for changes in the way that the body stores fat. In homeostasis, the body body’s fat processing mechanisms aren’t disrupted. However, when introducing a psychotropic drug and taking it over a period of time, the physiological changes that ensue may lead to storage of fats.
  • Hormonal changes: Many believe that Paxil is capable of depleting certain hormones when taken over a long term. Some believe that the mining of specific hormones is what makes Paxil stop working and weight gain likely. If you want to note any hormone changes, you could get your levels checked prior to taking the drug, and then again after you’ve been in treatment for awhile; then compare the results.
  • Metabolism slowing: Some experts believe that Paxil is capable of slowing the metabolism. This supports the idea that no matter how healthy and portioned a person’s meals, they will still gain weight when taking the drug. Many people have had this exact experience, which is why certain doctors are even buying into this theory.
  • Motivation drop: Certain individuals experience a major decrease in motivation when taking Paxil. While it may help their depression or anxiety, it may also make them relatively lazy. This is due to the sedating effects of the drug that are experienced in some people. Paxil can make it tough to get out of bed and exercise instead of watch TV and eat sugary foods.
  • Side effects: It is common to feel increasingly fatigued or sleepy when taking Paxil. Those that feel tired from this drug may be less likely to work out or even get adequate physical activity. The sleepiness may render them lazy for an entire day. If a person’s eating habits remain the same (or increase as a result of an appetite boost), they are going to gain weight.
  • Social eating: When people are depressed or anxious, they are less likely to go out to eat with friends and family. When their depression or anxiety is lifted through treatment, there’s a greater chance they will do some social eating. This means the person will go out to eat more frequently with friends and gain weight as a result of this new habit.
  • Taste improvement: Sometimes antidepressants seem to alter our neurochemistry in a way that food subjectively tastes better. It was already mentioned that people may have carbohydrate cravings and/or notice that carbs taste particularly delicious, but this can apply to all foods. If you notice that your taste is enhanced from the drug, don’t second guess your experience.

Note: Rather than honing in on one particular possibility or factor, it is important to consider that each individual scenario involving weight gain from Paxil is likely different. In many cases weight gain is due to an individualized combination of the factors listed above.

Factors that influence weight gain on Paxil

There are other important factors that need to be considered when taking Paxil. These include: the dosage you took, your individual genetics and physiology, the time span over which you took the drug, and whether you are on any other drugs.

1. Dosage

A good rule of thumb to follow is that the less of the drug you take, the less likely you are to gain weight. On the other hand, the greater the dose of the drug you’re taking, the more likely it is that you’ll gain weight. Unfortunately most doctors will prescribe whatever dose they want you to take, but in reality, they should always have you start low and titrate upwards to the “minimal effective dose.”

By finding the minimal effective dose, you decrease the likelihood of significant weight gain as a result of this antidepressant. Higher doses tend to alter our brain and nervous system to a greater extent than lower ones. This allows the drug to make more changes that disrupt homeostatic processes (potentially hormones, metabolism, etc.). The bottom line is that each time you double your dose, you may be doubling the amount of weight that you’ll gain.

2. Individual factors

It is important to account for individual factors that may be leading you to gain weight. Have you all of a sudden stopped exercising and eating a healthy diet? Have you become more stressed than you were in the past? While no one ever wants to blame themselves for the weight that they gained, it is possible that your particular lifestyle is contributing to the weight gain.

This would mean that not only is the drug leading you to pack on some weight, but you are doing nothing to combat the effects. Some people may be doing a lot to counteract the effects of the drug and may end up gaining only a minimal amount of weight.

3. Time span

Have you been on Paxil for a short period or a long term? People who take Paxil for several months may not notice any fluctuation in weight. In fact some people may actually lose a few pounds in the early stages of treatment. However, there is evidence supporting the idea that those taking this drug for a long term are likely to gain weight. The longer you take the drug, the more changes it makes within the nervous system, and the more likely it is that you’ll eventually increase the dosage (leading to further weight gain).

4. Other medications

It is highly important to consider whether other medications may be contributing to your weight gain as well. It is easy to blame the Paxil that you’re taking, but can you be sure that it’s the Paxil and not the other drug. Certain medications do have a tendency to cause weight gain – especially if they are psychiatric. Also consider the fact that both the other medication and Paxil may be contributing equally to the weight gain and in some cases may be synergistically promoting weight gain.

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/12410060

How much weight will you gain from Paxil?

Evidence is somewhat unclear regarding how much weight will be gained with treatment on Paxil. Experts like to generalize and promote the idea that you won’t gain any weight, but that’s not generally true. Some uncontrolled studies have suggested that on average, those taking therapeutic doses of Paxil for 6 to 12 months gain an estimated 24 lbs. – this is considered the highest of all SSRIs.  Some researchers however, like to generalize all SSRIs by stating that the weight gain is only roughly 10 lbs. throughout the entire course of treatment.

  • Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC181155/

Will everyone gain weight while taking Paxil?

No, not everyone will gain a significant amount of weight while taking Paxil. In fact, some people will actually lose weight in the early stages of treatment if they experience an activating effect from the drug. While many people will gain weight, it is important to highlight the fact that not everyone is destined for weight gain.

Some researchers speculate that individual genetic differences are often responsible for determining how someone reacts to the drug. This is why tests like GeneSight are being developed to determine how well your genetics will tolerate Paxil and its effects. In general, those who take Paxil for a shorter duration and at lower doses may remain weight neutral.

Paxil: Cost-Benefit Analysis

When taking any psychotropic drug, it is important to compare the costs (e.g. unwanted side effects) with the benefits (e.g. depression reduction). If weight gain is a big deal to you, first analyze how much weight you’ve gained directly as a result of taking Paxil. Then assess how well the drug is treating your condition.

If you’ve gained a small amount of weight, but are getting a huge benefit from the medication, it should be common sense to continue treatment. However, if you aren’t really getting any benefit from the drug (or are feeling worse) and are gaining weight, you will likely want to undergo Paxil withdrawal and/or switch medications. The main focus should always be on treating your mental illness, but if the drug isn’t really working and/or the weight gain is excessive, the drug probably isn’t a good fit.

Personal Experience with Paxil: Marginal (10 lbs.) Weight Gain

In my personal experience taking Paxil, I experienced very minor weight gain throughout my 8 months of treatment. My appetite increased, I craved unhealthy carbohydrates, and experienced bouts of lethargy throughout my treatment. I also did significantly more “social eating” with friends at various restaurants and wasn’t very selective with what I ordered.

My guess is that in those 8 months I gained roughly 10 lbs. At the time, I was still active in various athletics and regularly lifted weights, biked, and went for runs. When I was first on the medication, I had no knowledge of any potential side effects, and my last concern was weight gain.

Since I was still a teenager at the time, my guess is that my metabolism was still higher than most adults – so I had that working in my favor.  It should also be mentioned that I was taking Paxil CR 12.5 mg.  This meant I was on the lowest possible dose of the controlled-release version.

Did you gain weight while taking Paxil?

If you gained weight during your treatment with Paxil, feel free to share some details in the comments section below. It may help to know what dosage you were taking, how long you had been taking the Paxil, and any other factors that may have contributed. If you have successfully managed to keep weight off throughout your treatment with this drug, others may find benefit in you sharing your strategies.