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Phentaslim is a metabolism boosting diet pill that is available exclusively online from the official product website. The website describes numerous benefits in using the product and has been used by many thousands of customers to maximise their potential weight loss.

Below we take an in-depth look at Phentaslim to see how effective it is at helping with your weight loss goals.

Phentaslim Pros

  • Over 100,000 customers
  • Clinically proven weight loss quantities
  • Made in a “GMP” certified facility with solid ingredient profile
  • 60 day money-back guarantee

Phentaslim Cons

  • Only available direct from manufacturer- no price competition
  • Contains caffeine
Watchdog Approved Diet Pills

Phentaslim Review

Phentaslim Facts

  • Manufactured by Optimum Nutra Inc
  • 90 pills per bottle
  • Contains a range of clinically proven ingredients

Phentaslim is manufactured by a company called Optimum Nutra Inc. The Phentaslim website starts off with a testimonial from a happy customer who claims to have lost 32 pounds over a period of 5 weeks and extolls the virtues of using Phentaslim to achieve this.

It is said that this can be achieved as the product; increases the metabolism, reduces excess body fat, decreases hunger cravings, and increases energy levels. The product also claims to support good mental balance, good concentration and co-ordination.

The product is manufactured in Government inspected facilities that have met the highest standards of production. The company can be contacted using the information provided on the official website and some customers will like that there is a direct sales line to take phone orders.

Optimum Nutra Inc. have a excellent reputation for customer service, and we were unable to find any customer complaints about the company. We sent an inquiry via the contact form regarding some of the ingredients and received a detailed reply back within a couple of hours. It feels like they are aiming for a personal touch and put the customer first.

Phentaslim Benefits:

  • Uses clinically proven ingredients in the right amounts
  • Marketed as an effective fat burning and appetite suppressant that boosts energy
  • Full 60-day money-back guarantee and free worldwide shipping options

How to Take Phentaslim

Take three capsules per day. The manufacturers do not state on the website how best to distribute these three capsules, but we suggest taking two with breakfast, and the third capsule either with lunch or about an hour before exercise. Customers may also want to start with a lower dosage to assess personal tolerance levels.

What Does Phentaslim Claim To Do?

The manufacturer of Phentaslim describes the following benefits for the product:

  • Boost Metabolism – Ramp up your metabolism so that you burn more calories and promote your fat loss.
  • Longer Lasting Energy – Boosts energy levels without that crash and burn feeling, so you’re ready for anything!
  • Suppress Appetite – Suppresses your appetite so that you stop snacking between meals
  • Support Mental Performance – Supports good mental balance, good concentration and co-ordination.

So What Is Phentaslim and What Are The Ingredients For Phentaslim?

The ingredients used in Phentaslim are listed below. Each daily serving of three capsules contains a total of 1800 mg of the Phentaslim formula. The individual ingredient quantities provided below are per three capsule serving.

  • Green Tea (375 mg): Green tea is high in a group of antioxidants called catechins. Studies have suggested that catechins increase thermogenesis in the body, whilst caffeine increases energy expenditure by boosting the metabolism slightly for few hours.
    Source: http://ajcn.nutrition.org/content/70/6/1040.full
  • Caffeine (270 mg): Numerous studies have shown that caffeine boosts energy levels and alertness, as well as mildly boosting the metabolism. The effects shown in studies are small, and some studies are inconclusive.
    Source: http://www.mayoclinic.org/healthy-living/weight-loss/expert-answers/caffeine/faq-20058459
  • L-Theanine (225 mg): This amino acid may play a small role in weight loss, as well as increasing feelings of relaxation. It may also reduce the negative side effects of caffeine, although there is seemingly no strong clinical evidence to support this claim.
    Source: http://healthyliving.azcentral.com/ltheanine-weight-loss-6800.html
  • L-Carnitine (200 mg): There is some evidence that supplementation of acetyl-l-carnitine can reduce body fat, although the strongest results were seen in the elderly. The ingredient also boosts energy levels, and is used to treat fatigue.
    Source: http://examine.com/supplements/L-Carnitine/
  • L-Tyrosine (200 mg): Some people use Tyrosine as an appetite suppressant, but there is little clinical evidence that it is effective for this use. Large doses of tyrosine may be useful for increasing alertness, especially in people who are sleep deprived.
    Source: http://www.webmd.com/vitamins-supplements/ingredientmono-1037-TYROSINE.aspx?activeIngredientId=1037&activeIngredientName=TYROSINE
  • Panax Ginseng (120 mg): Panax Ginseng is associated with improved cognition in fatigued subjects and slight decreases in muscle damage after exercise. It also appears to reduce fatigue, and consumers report feeling calmer after consumption.
    Source: http://examine.com/supplements/panax-ginseng/
  • Guarana Seed (100 mg): A berry that is naturally high in caffeine, it is often an ingredient in energy drinks and diet pills.
    Source: http://en.wikipedia.org/wiki/Guarana#Other_uses_and_side_effects
  • Magnesium (80 mg)
  • Cayenne Pepper (50 mg): Capsaicin, which is found in Cayenne pepper, is thought by some to play a role in weight loss. Some studies suggest it could suppress the appetite mildly, whilst others suggest that the heat causes a thermogenic reaction in the body, burning more calories for a period of time. However, there are also studies that show cayenne has little or no effect upon weight loss attempts.
    Source: https://umm.edu/health/medical/altmed/herb/cayenne
  • Niacin (20 mg): Vitamin B3, or Niacin, is responsible for helping to produce energy from consumed food, as well as helping keep the nervous and digestive systems healthy. Niacin can be easily sourced in adequate amounts from a balanced diet. Persistent excessive consumption of niacin has been linked with increased rates of obesity in American Children.
    Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874142/
  • Zinc (15 mg)
  • Black Pepper Extract (6 mg): Black pepper extract (piperine) is used for increasing the bioavailability of nutritional compounds. In other words, it increases the amounts of nutrients that are absorbed into the body in the digestive tract. It may also increase the absorption of various drugs, which may lead to potential side effects.
    Source: http://bioperine.com
  • Vitamin B6 (1.8 mg): Vitamin B6 has several important functions in the body, including ‘allowing the body to use and store energy from protein and carbohydrates in food’. Whilst taking excess amounts of vitamin B6 will not infinitely improve this ability, a deficiency could make it more difficult to lose weight.
    Source: http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Vitamin-B.aspx
  • Vitamin B2 (1.7 mg): This vitamin is used for keeping the eyes, skin and nervous system healthy, as well as helping the body to release energy from carbohydrates. It is naturally present in milk, eggs, rice and fortified breakfast cereals, and so people should be able to get their daily guideline amounts from a healthy balanced diet.
    Source: http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Vitamin-B.aspx
  • Thiamin (Vitamin B1) (1.3 mg): The NHS states that thiamine is important for helping to break down and release energy from food. This may be relevant for maintaining a healthy metabolic rate, but in the majority of cases people can obtain all the thiamine they require from their daily diet.
    Source: http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Vitamin-B.aspx
  • Vitamin B12 (10 mcg): Vitamin B12 is naturally present in many foods, primarily meat, fish and dairy products. It has several roles, including aiding in releasing energy from consumed food, and keeping the nervous system healthy. It may be that a deficiency hinders weight loss, but taking excess amounts could be, according to the NHS, potentially harmful.
    Source: http://www.nhs.uk/Conditions/vitamins-minerals/Pages/Vitamin-B.aspx

So What Does All This Mean?

Whilst many diet pill manufacturers offer statements and make dramatic claims about how their product works to aid weight loss, very few offer evidence for their claims. The manufacturers of Phentaslim have included numerous links to the clinical trials they have referenced.

phentaslim holding bottleCaffeine will increase the bodies metabolism for a period of a few hours after consumption. The content for each capsule is about the same as a cup of coffee, and so spacing out the doses, taking two with breakfast and one with lunch or before exercise will maximise the energy boost and metabolism boost throughout the day. Theanine will help to counteract some of the “jitters” a few people experience. The inclusion of black pepper extract will likely increase the absorption of caffeine, enhancing its effects.

Green tea and cayenne pepper will both increase thermogenesis in the body, burning more calories in the process. Cayenne pepper may also have a small appetite suppressing effect, although studies suggest that this is small.

Acetyl-L-Carnitine and Tyrosine are both amino acids, and so can be used by the body to create muscle mass when the consumer is under-taking muscle building exercises.

The vitamins provided in this supplement are of an appropriate level compared to the recommended daily intake. Consumers should ideally not combine this product with other sources of caffeine or other B vitamin supplements.

Does Phentaslim Have Any Side Effects?

Whilst some of the ingredients used in Phentaslim can cause side effects in a very few consumers who are very sensitive to caffeine, the dosages are well-balanced to be effective whilst making side effects uncommon.

As with anyone who is taking prescription medication, you should consult your doctor before taking a product of this type. Theanine claims to help to counteract some of the potential side effects of caffeine, including any jitters.


Always swallow the capsules with water. Do not take if pregnant or nursing. If you have any medical conditions or are taking any medication, consult your doctor before use. Not suitable for anyone suffering from any heart related health issues, including but not limited to high blood pressure. Not suitable for those under the age of 18.

Any Phentaslim Reviews From Customers?

Numerous customers have left their feedback for Phentaslim here at Diet Pills Watchdog. A selection of these comments are below:

Started taking 1 of these each morning on Wed this week and am down 2 pounds already! Has given me the ability to get out of recliner and be the wife and grandmother Ive always wanted to be! Spotlessly clean house and flowerbeds are weeded. Been to the gym every day since starting these! Has really helped with my hunger and curbed appetite. I pray they continue to help like this!

I received my order in the mail super fast which was awesome. Best of luck to everyone who takes these, they’re great!

So after a full two month course on these pills, I am very happy to announce that I have lost two and a half stone in two months! I would recommend these to anyone hoping to get a head start on their weight loss as the extended energy, fuller feeling of stomach and ease of use make these HIGHLY commendable.

I ordered this product mid-April and am really liking it so far! Have lost noticeable weight (that people comment on). I do exercise regularly anyway so haven’t changed anything there, it’s just given me a much needed boost. The only thing I will say is that – as a big caffeine drinker myself – do not drink coffee while taking this product, at first I couldn’t sleep/was feeling a bit jittery. However when I cut the coffee down that all stopped! Good product if taken correctly!

Two weeks ago I was 20st 11.4lbs. Weighing this morning I am 19 st 11.6lbs. 0.2 pounds away from losing a stone in two weeks.
I have drank only water and eaten clean over the two weeks. The pills are amazing for helping to suppress your appetite but I recommend you have a small amount to eat after the 20 min recommendation of taking them or you will experience a weird stomach until some food is digested. The energy I am experiencing from these pills has really helped me down the gym and has finally kicked me into gear for losing weight. I highly recommend these pills for helping towards your overall diet and exercise plan but that’s all it is. A booster for your diet and exercise. You put in the effort and these pills will help you get the most out of what you do. 9.9/10.

So Does Phentaslim Work?

Both the ingredients list and the customer reviews we have located suggest that Phentaslim does aid weight loss without the side effects seen in other supplements.

Appetite suppression seems to be very effective for many consumers too, meaning this could help you to stick to a lower calorie diet plan you may be following.

Where Can I Buy Phentaslim?

Customers can order Phentaslim from the official Phentaslim website, and have a choice of several multi-buy purchase options that can make massive savings.

  • A single bottle of Phentaslim costs £39 ($69)
  • Two bottles costs £77 ($109)
  • and a “super value package” of four bottles costs £117 ($159).

In general, Phentaslim is a very cost-effective product.

Delivery is FREE on all orders (including international delivery).

Customers can securely pay either through Paypal, or on a Visa, Mastercard or American Express credit card. There is no auto-ship program or automatic repeat ordering, which we particularly like.

What About A Guarantee?

The manufacturers offer a 60 day money back guarantee on this supplement, which starts from the order date. This is valid for one opened bottle, and any additional bottles returned should be unopened.

Customers should obtain an RMA number from the company’s customer service department before sending the package, and should mark the RMA number clearly on the outside of the package.

Watchdog Verdict

Overall, we are very impressed with both Phentaslim and its manufacturer, Optimum Nutra Inc. The company clearly associate themselves with their own products on their official website, provide a company address, and follow high manufacturing standards for diet pills. They offer a 60 day money back guarantee; the returns policy is clear and easy to follow and all the information is available on the website. The claims the manufacturers make about the product are supported by references to clinical trials, and are not outrageous or ridiculous.

As for Phentaslim itself, it appears to have a solid ingredients profile, using appropriate dosages of the active ingredients. Numerous ingredients used in the product have strong clinical support, such as caffeine and green tea. The ingredients used also have a strong safety record.

The product has been around for quite a while and the number of positive reviews from happy customers that we found are very encouraging. The customer reviews also support the idea that if used properly and alongside a healthy diet and regular exercise, Phentaslim can help to accelerate the consumer’s rate of weight loss.

We Have no hesitation in making Phentaslim the number 1 choice for consumers and the editors top selection.

Watchdog Approved Diet Pills

Click here to Visit Phentaslim Official website!

Disclaimer: Our reviews and investigations are based on extensive research from the information publicly available to us and consumers at the time of first publishing the post. Information is based on our personal opinion and whilst we endeavour to ensure information is up-to-date, manufacturers do from time to time change their products and future research may disagree with our findings. If you feel any of the information is inaccurate, please contact us and we will review the information provided.

556 comments on “Phentaslim”

  1. Dewi says:

    Mostly in really sceptical about these things but I wanna try it I just wanna know if this really works because I go to the gym 7 days a week and I hope with the pills to lose weight because I’ve been looking very long and I’m very aware of what I buy so my question is does this really work ?

  2. Begoña De P says:

    Repeating a question from Lisa on March: What happens when u stop taking phentalism? Does it effect your metabolism in negative way after you stop taking them?
    Any news? Thanks!

  3. Samantha C says:

    Lol first day of taking the pills recommended last one 12.20pm and still awake 🙁 no obvious side effects though a bit of a spacey feeling at times. Mood defo boosted. Lack of appetite today. 4lbs lost in last 10 days without diet pill aid. Weight check next week. Just starting to feel tired now ……..

  4. sean says:

    I live in South korea, and there seems to be no options for South Korea in country. How can I get it to deliver?

  5. ggg says:

    do you hae to excerisse with this product ?

    1. osiris says:

      If you read the comments above, you’ll find that you definitely need to exercise. It is called a “supplement” for a reason, it is NOT the main thing that will make you lose weight but will help with the process; diet and exercise is still needed. Just like what the editor of this site mentioned, there is NO “magic pill” in existence. So if you are looking for a pill that will make you lose fat while you just sit in the couch and eat, I suggest you give up ’cause there is none.

  6. Samantha C says:

    Just ordered my first batch as need to lose the baby weight (though ‘baby’ is now 3yo!). I’m dubious about whether it will work but feel I need a boost as I’m so tired all the time, working full time and looking after my family. It’s great to hear its worked for some of you and I’ll let you know how I get on. I have (ideally) 40lb to lose. I have been on a low calorie diet for past week so hoping this helps me stick to it. Just need the energy now to do more exercise. Can’t wait to try them 🙂

  7. Rita Christen says:

    Can I take Phentaslim while taking medication for high blood pressure?

    1. Annabelle says:

      Hello, can I just point out that most GPs wont know if these ingredients will be contraindicated with common medication like thyroxine or treatments for hypertension. When the manufactures say anyone with heart disease should not use it, can you get them to clarify exactly what type of heart disease. Most overweight people will have some furring up of their coronary arteries. Is this what they mean? Are there any recorded deaths from this product ? I would really like to see more data before I try it. Many thanks Annabelle United Kingdom

  8. Ashley says:

    I have been taking Phentaslim for a little over 3 months. I am ecstatic with the results. I have lost 22 lbs so far. The pills give me a good boost of energy without making me feel jittery. My appetite has also been decreased. Another major positive thing is NO CRASH! I’ve tried my fair share of diet pills (including doctor prescribed Phentermine) and one of the worst side affects is the resulting crash they can cause. I love this product and am extremely happy with the results.

  9. Manisha says:

    Hello. I have been exercising and religiously following a very healthy diet plan for past 3 months. Although I lost weight initially, I have almost stagnated now. I still need to lose a good 15-20 pounds. With my current diet, I am not short of energy, neither am I hungry between meals. Just wanted to know if this pill will be helpful in kickstarting the weight loss again?
    Also, after losing the weight do I need to continue with the pill for maintaining the weight?
    Thanks for all the useful information you have posted here. Being an entrepreneur myself, I understand the need for funding, especially for a good cause. If I do decide to buy this pill, I will definitely follow the link from your website!

  10. Steph says:

    Hi, I normally dont bother leaving reviews because I am never 100% sure how real they are. I thought this would be too strong for me, I go to the gym 1-2 times per week but have struggled to lose that little bit of fat that helps me look toned. I gave these a go, was happy with the service and fairly quick delivery in 2 days. The caps certainly gave me more energy great for getting to the gym… in a little over 10 days lost 5 1/2 pounds. Cant complain these have certainly helped me… my only grumble is the reported “improved mood”, didnt have any noticeable changes in mood. although I am happy at the weight loss!

    1. Moka Blu says:

      Hi, Steph. Have you lost anymore weight since you last reported on March 18th?

  11. may grew says:

    its obvious there’s no magic pill.most diet pills are to help with energy levels, suppress appetite,less you eat more exercise you do get rsults. good old diet and exercise with a helping hand of one of the many pills available to give you that extra energy.or vitamins you arent eating.thermabol is the best pills i have for increased energy when reducing calories.

    1. Watchdog Staff says:

      Hi May,
      You’re indeed correct there is no magic pill… just look at the effectiveness of prescription diet drugs and surgery, both of which take time and require action from the dieter. No solution is the result of any quick fix.
      There are over the counter supplements thought that can help. As you have suggested Thermobol is a good product that works, although probably not the most suitable supplement for most dieters due to the strength and possibility of side effects. That’s why Phentaslim we have seen as a product that offers the benefits of Thermobol with less of the stimulants.
      We’d like to hear from maybe consumers who have given both a try.
      Diet Pills Watchdog

  12. vivienne says:

    I was wondering if anybody had tried the phentaslim and if so what sort of results they got. I am looking to supress appitite

    1. Tracy says:

      hi vivienne, I gave one bottle a go around 3 weeks ago and noticed more energy straight away. Never been keen to exercise these pills made me up for it. Lost 3 pounds the first week since then another 6 pounds. Weight loss did slow down after first week but its worked for me. I am going to order again in a few days time 🙂

  13. Irene K says:

    I have never had to diet before but suddenly found this last year I have gained 2 stone, I have joined a gym working hard with no results as yet(early days), I have just sent for Phentaslim and hope they suppress my hunger and help me lose this weight. I know age has got something to do with it as I shall be 75 this spring. Wish me luck it won’t be for the want of trying, I am for ever hungry and am really strict with my diet I shall be happy to let you know my progress once the pills arrive.

  14. tan says:

    hi im am on a very low carb diet , high protien. finding it difficult inbetween meals…so have been researching differant things! so its now a choice between PHENTASLIM or PHEN375. iv read both you reviews. could you tell me which u would say is better !! also am i correct in saying that they both do the same thing?? thanks!!

  15. Adriana says:

    Is this products made in the US?

    1. Watchdog Staff says:

      Hi Adriana,
      The supplement according to the manufacturer is made in the US. The bottle we have seen also shows a “made in USA” stamp.
      Diet Pills Watchdog

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