Is Plenity The Same As Phentermine?
In our latest question and answer, the pharmacist discusses the difference between Plenity and phentermine.
I saw a commercial for Plenity for weight loss. I have taken phentermine before and it wasn't what I expected. Is Plenity similar?
Jun 24, 2022- Plenity is a medical device made of cellulose hydrogel particles that expand in your stomach to create fullness, while phentermine is a prescription drug that works by affecting brain chemicals to reduce appetite. Phentermine is typically used short-term for up to 12 weeks and tends to produce greater weight loss, but it carries more side effects and abuse potential than Plenity. Plenity can be used long-term without a time limitation and has fewer side effects, though it may cause digestive issues like diarrhea and bloating.
Hello and thanks for reaching out!
Although Plenity and phentermine sound similar, they are two very different things and work differently to help support weight loss.
First and foremost, Plenity isn't even considered a 'drug', but rather a medical device by the FDA.
Phentermine, on the other hand, is a prescription drug, chemically similar to stimulant drugs like amphetamine.
Both Plenity and phentermine have their positives and negatives, which I touch on in the next sections.
How Does Plenity Work For Weight Loss?
Plenity is considered a 'hydrogel' product.
Every capsule contains thousands of cellulose hydrogel particles that expand in the stomach.
The hydrogel particles in every Plenity dose expand to occupy about 25% of the total stomach space, creating a feeling of fullness and satiety. Essentially, the expansion of the hydrogel particles leaves less room for food.
For best effects, each dose should be taken with about 16 ounces of water and be taken at least 20 to 30 minutes before food. This will allow the water to be absorbed into the particles, which will, in turn, create a feeling of fullness.
I mentioned that Plenity is considered a medical device, and not a drug. This is because our bodies do not metabolize or absorb the hydrogel particles. They will just eventually pass through your gastrointestinal tract.
Currently, Plenity is only available after a telemedicine visit online but is slated to be available in pharmacies in the future.
How Does Phentermine Work For Weight Loss?
Phentermine is classified as a 'sympathomimetic', and it is similar to stimulants, like amphetamine and methylphenidate.
These types of drugs have a complex mechanism of action, but in regard to helping support weight loss, they work by stimulating the release of the neurotransmitter norepinephrine and/or inhibiting its reuptake.
This generally results in a reduction of appetite and causing a feeling of fullness.
Important Differences
There are a number of important differences between phentermine and Plenity, and I've outlined the major ones in the chart below.
As an overall assessment, phentermine likely is more effective than Plenity, but you have to consider the fact that it is a controlled substance, has more side effects, has abuse potential, and has more drug interactions.
| Phentermine | Plenity | |
| How It Works | Stimulates the release of norepinephrine, causing a reduction in appetite | Cellulose hydrogel particles expand in the stomach, creating a feeling of fullness |
| Length Of Use | Labeled to be used short-term, up to 12 weeks. It may be used longer in some | No limitation on the duration of use |
| Cost | ~$0.40-0.60 per capsule/tablet | ~$1.75 per dose (recommended at two doses per day) |
| Side Effects | Increase in blood pressure and heart rate, nervousness, constipation. Controlled substance with abuse potential | Diarrhea, bloating, nausea, vomiting, constipation |
| Average Weight Loss | ~17 pounds after 12 weeks at 37.5mg daily | ~6-7% total body weight after 24 weeks |
| Drug Interactions | Several, including antidepressants and some over-the-counter medications | Do not take at the same time as other medication |
Final Words
Thanks again for reaching out to us!
If you have any additional questions regarding phentermine and Plenity, we are more than happy to answer them!
References & sources
Glossary — Terms in This Answer
- Medical device
- A product regulated by the FDA to help diagnose, treat, or prevent disease but not classified as a drug.
- Hydrogel
- A gel-like material that can absorb water and expand in size.
- Satiety
- The feeling of fullness and satisfaction after eating.
- Gastrointestinal tract
- The system of organs in your body that digests food and moves it through your stomach and intestines.
- Sympathomimetic
- A type of drug that mimics the effects of the sympathetic nervous system to produce stimulant effects.
- Neurotransmitter
- A chemical messenger in the brain that transmits signals between nerve cells.
- Norepinephrine
- A neurotransmitter in the brain that helps regulate appetite and alertness.
- Controlled substance
- A drug regulated by the government due to its potential for abuse or dependence.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
More answers from Brian →