Updated: 05/17/2016 - Website operated by Leptigen

Phentaslim Review - Does This Weight-Loss Supplement Really Work? Are fad diet ingredients and negative user reviews deal breakers?

Editor's Review: 3.5 / 5.0
Phentaslim Review

Looking at some diet products can be painful, especially if there’s no scientific backing for the formula. Let’s find out if Phentaslim is in this group. We did some intensive research and created one of our in-depth reviews, examining the side effects, ingredients, clinical studies and overall customer service. Also, we scoured hundreds of dieter experiences found online. At this point we compressed all the data to give you the info you need.

EDITOR'S TIP: Substitute Phentaslim with a proven fat burner such as Leptigen for better results.

What You Need To Know

To start, Phentaslim is a weight-loss product made by Optimum Nutra Inc. The ingredients are guarana seed, caffeine anhydrous, green tea extract, magnesium, zinc acetate, cayenne pepper, panax ginseng root, L-tyrosine, L-theanine and L-carnitine. This supplement is fine for women and men trying to lose weight. According to the company website, Phentaslim helps by boosting energy levels, decreasing hunger and food cravings and reducing excess body fat. This should be taken 20 minutes prior to breakfast, lunch and dinner along with a glass of water.

Phentaslim has been available since 2012 and can be purchased via the official website for $59.99. This supplement is backed by a 30-day satisfaction guarantee and there are some user testimonials posted on the website, but read on…

Fad Diet Ingredients – “No Proof?”

The first thing we felt needed attention with Phentaslim ingredients was the fact that some are nothing more than a fad. “Phentaslim relies on an unproven formula that contains cayenne pepper and panax ginseng root, neither of which has been proven to assist with weight-loss or fat reduction. This is certainly concerning,” says our Research Editor.

One customer stated, “Not effective at all. Been taking for six weeks now.”

“Another scam pill. Doesn’t work like it’s supposed to.”

Scroll below for one of the best products we’ve seen over the last year.

Negative User Reviews – “That’s Not Good”

It’s always a good idea to check out customer reviews posted online. We discovered that one person stated, “I started Phentaslim on 6th Dec. Not seen any weight-loss yet. But I feel more energy. But since couple of days I am feeling dizziness and heavy head after consuming the medicine. The headache is quite a lot.”

Another said, “Serious jitters and nausea from this diet pill.”

After doing some extensive research, we came to the conclusion that if there is an individual aspect of a fat loss pill or diet system that is quite troublesome (too many negative reviews, fad ingredients, serious side effects) the true likelihood of lasting weight-loss results is minimal. This means if Phentaslim does result in a lot of discouraging claims, this could be a serious dilemma.

The Science – “Clinical Backing?”

Even though the official website states that Phentaslim uses ingredients that are supported by clinical research, we could not find the actual studies presented by the company. Here at DietSpotlight, we need to see documentation of real science before we can get behind a weight-loss product.

The Bottom Line – Does Phentaslim Work?

Well now, has the time come to rush out for this one? While there is definitely a lot of hype surrounding Phentaslim capsules, we aren’t comfortable recommending this weight-loss formula. The reality is there are only two customer testimonials posted on the official website and it does use some fad diet ingredients. Not to mention, Phentaslim is associated with side effects.

If you want to see more fat loss results, we advise you to select a supplement that is supported by plenty of positive customer reviews, does not cost a fortune and does not rely on fad diet ingredients.

Among the best products we’ve seen in 2016 is one called Leptigen. This supplement contains four unique ingredients, which have been shown via clinical testing to help enhance fat loss and increase metabolism. Customer comments found on the internet show people are seeing amazing results.

We find it a show of confidence that the company behind Leptigen is offering a Special Trial Offer, which is a good sign.

Learn More About Leptigen »
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How Does Phentaslim Compare?

Previous Phentaslim Review (Updated June 17, 2014):

What You Should Know

Click Here To See Our Highest Rated Review

Phentaslim is a fat burning, weight loss supplement that looks pretty fantastic at first glance. A complete list of ingredients, with amounts for each, contact phone number and clinical support for ingredients are all listed on the official website, but when we looked deeper into the company there are a few red flags customers need to know about.

List of Ingredients


  • Thiamin
  • Riboflavin
  • Vitamin B6
  • Vitamin B12
  • Zinc
  • Niacin
  • Guarana Seed
  • Caffeine Anhydrous
  • Green Tea Extract
  • Cayenne
  • Raspberry Ketones
  • L-Tyrosine
  • L-Carnitine
  • 5-HTP
  • Panax Ginseng Root

Product Features

The first six ingredients in the formula are nothing more than everyday vitamins. Pull out that bottle of vitamins you take every morning and you’ll likely find every one of these ingredient in higher doses, most of the time. Taking more of these vitamins and minerals is not going to improve overall health or weight loss. B vitamins are often marketed to increase energy, but the short half-life and the body’s inability to store the vitamins means a barely noticeable bump in energy before the body pushes those B vitamins out during urination.

Moving on to the active ingredients, we notice nothing spectacular. Guarana, green tea and caffeine are all proven to boost energy and metabolism. What dieters are looking for is this huge bump in energy and mood so they feel like eating right and exercising. That is not exactly what Phentaslim will provide. We like the fact that Phentaslim adds only 100 mg of caffeine, but guarana and green tea are both sources of caffeine, so there is more than 100 mg per serving. We have no idea how much caffeine these ingredients add, but if both are standardized to just 50 mg of caffeine the dose jumps to 200 mg per serving. We found no appetite suppressant in Phentaslim, another huge problem. Caffeine increases metabolism and thus increases hunger.

A hidden problem with Phentaslim is revealed in the terms and conditions. If order Phentaslim and you just don’t like the product, you can return it for a refund, but you will pay $10 for the return, you will not receive a refund for and original or return shipping costs and the company retains your personal contact information to sell or share with other companies.

See Our Featured


  • All ingredients are listed online.
  • Not too much caffeine is included per dose.


  • There are multiple stimulants in the formula.
  • The company charges a return fee.
  • Your personal information will likely be shared with other companies.


Most of the ingredients in Phentaslim are well-known, clinically tested and safe for use by healthy dieters, but the gauge of a good company is about more than just the ingredient list. Behind the scenes we find a company that sells or shares your personal information and charges you to return the product if it doesn’t work for you. You can find a more effective supplement from a trustworthy company.

Phentaslim Questions & Answers:

We boiled down hundreds of user comments about Phentaslim into this helpful FAQ.

What are the side effects of Phentaslim?

Phentaslim side effects may include jitters, nausea, dizziness, and headache.

What are the ingredients in Phentaslim?

Phentaslim ingredients are green tea, caffeine, l-theanine, l-carnitine, l-tyrosine, panax ginseng, guarana seed, magnesium, cayenne pepper, niacin, zinc, black pepper extract, vitamin B6, riboflavin, thiamin, and vitamin B12.

Does Phentaslim work?

The Phentaslim formula is not bad. It contains green tea and caffeine, two important ingredients. However, you can find these in hundreds (if not thousands) of other products. Some parts of the supplement have no clinical support.

You may want to change out Phentaslim for a product with strong customer support, like Leptigen.

How much does Phentaslim cost?

Phentaslim costs $59.99 for 90 capsules.

How should I take Phentaslim?

You should take Phentaslim three times a day, once 20 minutes before breakfast and lunch and once in the late afternoon. It is not suggested to take Phentaslim after 5pm.

Can I take Phentaslim if I have a health condition?

You should ask your physician if you are under the age of 18, if you are taking prescription medications, have other underlying health problems, are pregnant, or nursing.

What do users like about Phentaslim?

Users liked that Phentaslim may curb appetite, increase energy levels, and there is a money-back guarantee.

What do users NOT like about Phentaslim?

Users don’t like how Phentaslim has multiple stimulants in the formula and how pricey it is.

How do I contact Phentaslim customer service?

You can contact Plentaslim customer service by emailing them at cs@phentaslim.com or by going to their contact page.

Is there an official website for Phentaslim?

Yes, there is an official website for Phentaslim.

Do you know how much of each ingredient is in the formula?

Yes, the amount of each ingredient used in Phentaslim are listed on the official website.

Does Phentaslim come with a guarantee?

Phentaslim has a 60-day money back guarantee.

Do you know of any special deals or discounts on Phentaslim?

Yes, if you buy multiple bottles of Phentaslim, you can save at least $25.00. Lately, we’ve seen a huge uptick in customers taking advantage of Leptigen’s Special Trial Offer, which is just the cost of shipping and handling. Click here to give it a shot.

One User Review About Phentaslim

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    How long before I would expect to see results?


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