Phentaslim is a dietary supplement manufactured by the company Optimum Nutra, Inc. and is designed to assist in weight loss.
The product contains a variety of ingredients, many of which are common in weight loss products. My concern is not whether or not it works, but how it is marketed with clever deception! (see below…)
The makers of this supplement claim that it helps users to lose weight by increasing metabolism, reducing appetite and making users feel more energetic.
Are online reviews trustworthy?
Shopping around for weight loss supplements can be incredibly difficult. There are so many different products and most of them don’t have any kind of data backing up their claims. Hence, potential customers search for online reviews. This is where manufacturers grab the opportunity and cook-up great stories posing as independent reviewer! Is Phentaslim one of these supplements, or is it one of the relatively rare diet products which really does what it says and can prove it with real facts?
Negative Users Feedback
Many users have left negative reviews below on comments form. Therefore, we feel that Phentaslim is not as great as it is claimed to be. Please read about PhenQ, our top rated diet pill here.

This fat watchdog loves Phetaslim!
Watchdog approved v/s watchdog rejected
A supplements review website called dietpillswatchdog.com is heavily promoting it on their site. They write bad reviews of competitors products and almost all other diet pills are “watchdog rejected!“.
This watchdog has tested and written 100’s diet supplements review. Interestingly, this is the similar tactics used by another suspicious product called Leptigen. and more recently Sletrokor
Research based reviews provides some insight to customers. However, when the intention is clever self promotion, it is a bad practice.
What’s In Phentaslim? The ingredients
The ingredients of this product include caffeine, green tea extract, guarana, zinc acetate, magnesium, ginseng, cayenne and the amino acids L-theanine, L-carnitine and L-tyrosine, most of which you’ve probably seen in other weight loss supplements.
Now let’s have a deeper look at Phentaslim’s primary ingredients and it’s clinical studies.
Caffeine is a common substance in the diets of most athletes and it is now appearing in many new products, including energy drinks, sport gels, alcoholic beverages and diet aids.The evidence clearly shows that levels of caffeine consumed by most people have largely positive effects on behavior. Excessive consumption can lead to problems, especially in sensitive individuals. http://www.ncbi.nlm.nih.gov/pubmed/12204388
Guarana – A double-blind, placebo-controlled, multi-dose evaluation of the acute behavioural effects of guaraná in humans.Guaraná improved secondary memory performance and increased alert and content mood ratings. The two lower doses produced more positive cognitive effects than the higher doses. http://www.ncbi.nlm.nih.gov/pubmed/16533867
American Ginseng – Laboratory studies in animals have found that American ginseng is effective in boosting the immune system, and as an antioxidant. Other studies show that American ginseng might have therapeutic potential for inflammatory diseases. Research on American ginseng has focused on a number of conditions, including the following. http://umm.edu/health/medical/altmed/herb/american-ginseng
Korean Ginseng – The Effect of Korean Red Ginseng Supplementation on Glucose Control in Subjects With Impaired Fasting Glucose, Impaired Glucose Tolerance or Newly-diagnosed Type 2 Diabetes Mellitus
https://clinicaltrials.gov/ct2/show/record/NCT01911663
Phetaslim producer doesn’t mention which Genseng they are using. There is American Ginsenf and Korian Ginseng. Hence, I have provided link to 2 different clinical trials above.
The Pros:
- Made from natural ingredients, many of which are known to be at least somewhat helpful for weight loss
- Not known to cause any serious side effects. Side effects are mild.
- At about $60 for a month’s supply, pricing is in line with similar supplements available online (though pricey)
The Cons:
- Some have said that the product relies too much on fad diet ingredients like ginseng and cayenne. Noner of which has been proven to assist weight loss
- A number of users have reported mild side effects including headaches, nausea and jitters, likely from the caffeine content of the supplement
- No meaningful clinical studies provided by manufacturer
Common Questions and Answers
Q. How Much Weight Will I Lose?
Q. Will Phentaslim Stop Me Sleeping?
Q. Are There Any Side Effects From Taking Phentaslim?
How to use it for best result?
It’s recommended that this product be taken with a full glass of water, about 20 minutes before every meal. Phentaslim has been around since 2012 and is covered by a 30-day guarantee with $10 restocking and handling fees.
Does Phentaslim Work?
Let’s talk about what everyone really wants to know about this supplement – does it work? There’s certainly a lot of talk about this product, but what we haven’t really seen much of is user testimonials. Furthermore, there is no peer reviewed clinical studies providing real information about whether Phentaslim is effective.
Potential Side Effects
There’s is an issue of side effects for some people who are sensitive to caffeine. Headaches, nausea and nervousness from the product are common. At the same time, there are some people who swear by this supplement. Since it’s relatively affordable, it may be worth giving a try. If you’re looking for a weight loss product which contains metabolism boosters like caffeine, guarana and green tea extract, you can give a shot to Phentaslim.
Where to buy?
It is normally available on official website only. However, you can try similar products on Amazon for lesser price.
The Final Verdict:
Phentaslim can work in combination with calorie restricted diet and good exercise. If you are looking for an alternative you can try Phenq, which is our recommended product. With that conclusion I’m giving it 3 star.





That $10.00 restocking fee is scary. When someone returns the product opened, are they reusing / restocking the pills that are in the returned bottles? Gosh I hope not, but this doesn’t tell so I’d rather not take the chance!
No, not likely. This is a common ploy to get a bit more money off you because a “restocking fee” is permitted under the distance selling regulations.
Their website states they have a 100% money back guarantee, but beware!!! These diet pills DO NOT work. Once you buy them, you own them because they will not refund your money as they advertise. Don’t waste your money.
I don’t trust any reviews. All in it for something. Won’t bother buying this or any other . Will stick to diet and exercise.
That’s exactly what everyone should be doing 🙂
Warning! Although they will refund you within 60 days (minus £10) if you are not happy with the product – you can only trial a maximum of 30 days (1 bottle) before you decide. If you have opened more than 1 bottle – NO REFUND. This product did not work (I GAINED weight!) – and caused a horrible burning pain in my oesophagus for a good 30 minutes after taking the capsules. Waste of money and no refund. Very disappointed.
Hi. I have recently bought these phentaslim caps.. iv taken them for 2 days now and not had any side affects.. I will update in a few weeks to say if I have lost any weight.
Any update on the affects?
Did u lose any weight? Lol
Have the pills worked?
Just received it on the 6th March, so far I am having less appetite and being thirsty all the time. Trousers are getting loose. Will update again after a month.
any updates??