Updated: 01/12/2018

We’re hearing a lot of buzz about Fastin-XR diet pill, so we dug deep into the ingredients, side effects, and clinical research. We collected comments from hundreds of user reviews and statements. Then, condensed and summarized to give you the info you need.

Fastin-XR Readers: Click here to find out why we're giving away samples of our product, Burn HD.

What is Fastin-XR?

First off, Fastin-XR is a weight-loss supplement. The ingredients are:

  • Caffeine
  • 1,3 DMAA
  • Methylsynephrine
  • Phenylethylamine
  • Acai Rigdula Extract

Fastin-XR also contains synephrine, theobromine, green tea, naringin, methoxytryptamine, and yohimbe. [1] [2] You’ll take up to three capsules a day. It claims to boost energy and help you lose weight.

The product, introduced by Hi-Tech Pharmaceuticals after the company started in 1993, lists some of the ingredients online, a positive. We like that we found a few positive comments and the favorable BBB rating, but read on…

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Fastin-XR Side Effects – “A Major Issue?”

The first issue deals with Fastin-XR side effects. “The formula contains more than one stimulant,” said our Research Editor. “But, the combination could lead to adverse reactions.”

“I was very positive when purchasing this based on the reviews but when I took 1 tablet, my heart was racing. Tried 1/2 tablet and still the same result,” explained a dieter.

“I tried a whole tab and I thought my heart rate was way too fast,” said a user.

Other customers didn’t mention Fastin-XR side effects.

“It made my heart race, but I realized I was taking too many. I was okay when I cut down to one,” reported a customer.

FDA Action – “What’s That About?”

Hi-Tech Pharmaceuticals has been the subject of multiple FDA investigations. The latest letter sent to the company was in April 2015. According to the communication, several products, including Fastin-XR were mislabeled. They were told to stop selling all supplements claiming acacia rigidula was a source of Beta-methylphenethylamine. We checked the official website and it appears they have complied with the order.

Ineffectiveness – “Losing Weight?”

Based on user reviews, Fastin-XR ingredients don’t produce results. “After giving the product a full month I found it pretty worthless,” reported a user.

A dieter said, “I have been on this for 30 days and have been watching my intake. I haven’t lost a pound, in fact I gained a couple. I do not recommend this product, I am going to try something else.”

We found that some Fastin-XR reviews offered another side of the story.

“Jump starts the energy, but nothing too terribly bad,” said a customer.

“No negative side effects so far,” offered another.

Based on our research, it takes one thing, like side effects, to ruin your chances of long-term success. If Fastin-XR causes jitters and shakes, among other reactions, the dieter may stop taking it within a few days.

The Science – “Where’s the Proof?”

All you get from Hi-Tech Pharmaceuticals is a long description packed with product claims. We didn’t find a single reference to clinical studies. We were able to locate research supporting caffeine as a metabolism-booster, but it didn’t point toward this formula. Both synephrine and 1,3 DMAA are associated with negative side effects. The fine print for Fastin-XR does say it can cause issues with BP and it may interact with medications.

What Users Are Saying

“Just purchased Fastin-XR 3 days ago. Wow, this product gives you tons of energy! My appetite has decreased while having the desire to be physically active. Within 30 minutes after taking the capsule I got a little rush inside, similar to the feeling after drinking a strong cup of coffee. That’s the only side effect that I’ve had. No need to drink any caffeine drinks with this product.”

“Compared to the regular Fastin it works better as an appetite suppressant and is longer-lasting, but doesn’t give you as much energy as the original does.”

“This stuff works but it gives me such a bad headache when I use it every day. Every other day is not too bad but then it’s not as effective. For the high cost and headaches, I won’t be using this again.”

The Bottom Line – Does Fastin-XR Work?

So, are Fastin-XR diet pills the real deal? Well, we like the longevity of Hi-Tech Pharmaceuticals hand the low price. But, we have concerns about this one because there’s no research supporting the claims. There’s also an issue relating to customers comments about it potentially causing negative side effects, or producing results.

If now is your time to lose weight, we suggest going with a supplement that gives you clinically-tested ingredients and not linked to harmful side effects.

Among the best products we’ve seen this year is one called Burn HD. The formula consists of four clinically-tested ingredients, that have been shown to help boost fat loss and spark metabolism. We’ve not found a single dieter talking about harmful side effects, but we found plenty telling others about seeing great results.

Also, the company that makes Burn HD is confident in the product, so they’re offering a 2-Week Sample.

Learn More About Burn HD »
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Fastin-XR Ingredients

Fastin-XR Ingredients and Supplement Facts

Serving Size: 1 Capsule
Serving Per Container: 45 Capsules
Amount per Serving% DV
Caffeine Anhydrous150 mg*
Proprietary Blend375 mg*
Acacia Rigidula Extract**
Phenylethylamine Alkaloids**
Synephrine HCI**
Green Tea**
5-Methoxytryptamine HCI**
Yohimbine HCI**

Other Ingredients: None

We took a close look at Fastin-XR ingredients to give you the facts.

Acacia Rigidula Extract

Sometimes called blackbrush acacia or vachellia rigidula, acacia rigidula extract comes from a type of shrub. It grows in regions like Texas and certain parts of Mexico.

What is it Supposed to Do?

Well, acacia rigidula contains amines and alkaloids. These include hordenine, catechin, nicotine, phenethylaimine, tyramine, and tryptamine. Together these components are supposed to help suppress appetite and increase metabolism. This in turn helps with weight-loss.

According to the FDA, “Products whose labels claim to contain Acacia rigidula are commonly marketed for weight loss, supposedly by suppressing appetite and burning fat. But 9 of the 21 dietary supplements tested were found to have an unnatural compound, called beta-methylphenethylamine, which is structurally similar to amphetamine.”

Clinical Research

There have been some clinical studies done with acacia rigidula. According to WebMD, “Acacia rigidula contains many different chemicals that have stimulant effects. Because of this, it is often promoted for weight loss and athletic performance.” However, it goes on to say that there is insufficient evidence to support this ingredient for weight-loss.


First off, isopropylnorsynephrine is a lipolytic agent. It’s similar to synephrine, which is found in citrus aurantium or bitter orange fruit. It is also known as betaphrine or isopropyloctopamine.

What is it Supposed to Do?

The purpose of isopropylnorsynephrine is to boost metabolism, increase energy levels, reduce appetite and enhance focus. It’s often combined with other stimulants and herbs to help promote weight-loss.

Clinical Research

According to the National Institutes of Health, “Isopropylnorsynephrine is a stronger lipolytic agent in human adipocytes than synephrine and other amines present in Citrus aurantium.” One study showed that this ingredient might be useful for weight-loss. However, clinical trials involving human subjects are needed.


If you eat chocolate, then you’ve had theobromine. It’s actually the principle alkaloid in the cacao bean. Also called xantheose, this substance is a stimulant and diuretic.

What is it Supposed to Do?

Since theobromine is a mild stimulant, it can help keep you alert and boost energy levels. It may also help suppress appetite to some degree, and even elevate mood. There are also some claims that it aids with weight-loss.

Clinical Research

One 2005 study from the American Journal of Clinical Nutrition said, “Healthy participants were given dark chocolate — which contain high amounts of theobromine — for 15 days, and then switched to white chocolate, which contains none. Researchers found that dark chocolate significantly improved insulin sensitivity, which is an important aid in controlling body weight.” Therefore this ingredient may help with weight management on some level.

Is There Anything Out There That We Think TRULY Works?

We have our eye on a supplement that fits the bill. Dietspotlight Burn, which is formulated with ingredients that HAVE been clinically tested, may be a good option. All customers can take advantage of a Special Trial Offer, currently available. Click above to give it a try.

  • References
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Previous Fastin-XR Review (Updated September 23, 2014):

Fastin-XR: What You Should Know About

You may turn to one of the various online supplement stores for a weight loss product. It is no secret that dozens of these diet pills and weight management supplements are available online. Some even contain proven fat loss ingredients. Among these diet pills, you will find Fastin-XR, which is brought to you by Hi-Tech Pharmaceuticals. It is available for around $80 per bottle, and does not require a trip to the doctor for a prescription. But, does this weight loss formula yield real results? We will go over the specifics in this review. Ingredients:
  • Caffeine Anhydrous 150mg
  • Theobromine
  • Yohimbine HCL
  • DMAA
  • Green Tea Extract
  • Naringin
  • Synephrine
  • 5-methoxytrytamine HCL
  • Acacia Rigidula Extract
  • R-beta-methylphenylethylamine

Fastin-XR: Product Features

Fastin-XR can be taken daily in order to aid with weight loss. This supplement contains a number of key ingredients to potentially improve the metabolism, elevate mood, burn off fat, provide antioxidant protection, suppress appetite, and boost thermo genesis. There is no low-fat diet required with Fastin-XR, and this formula is okay for women and men, 18 and older. However, there does not appear to be a refund guarantee offered. In regards to the ingredients found in Fastin-XR capsules, they include Caffeine Anhydrous (this is a stimulant and diuretic that may improve energy), Green Tea Extract (contains caffeine and antioxidants to boost the metabolism), Theobromine (this is a stimulant and mood enhancer that may help eliminate excess water weight), Yohimbine HCL (a stimulant that helps improve metabolic rates for fat burning), Naringin (grapefruit extract that suppresses hunger), Synephrine (an alternative to Ephedra that increases thermo genesis), Acacia Rigidula Extract (boosts energy levels and curbs hunger), and R-beta-methylphenylethylamine (suppresses appetite).

Advantages of Fastin-XR

  • The ingredients used in this weight loss formula are revealed online.
  • Fastin-XR requires no prescription.
  • This diet product contains antioxidants to fight free radical damage.

Disadvantages of Fastin-XR

  • This diet pill contains Synephrine, which acts like Ephedra.
  • There are four different sources of caffeine used in Fastin-XR.
  • The stimulants in this weight loss pill might lead to side effects.
  • There is no guarantee available with this dietary supplement.

Fastin-XR Conclusion

There are plenty of diet pills and weight loss products that are loaded down with stimulants. Fastin-XR is no exception. After all, this supplement contains four types of stimulants, in addition to Synephrine. Synephrine is basically an alternative to Ephedra, and it causes similar effects. Therefore it may also lead to similar side effects, which can be dangerous. Therefore we do not recommend Fastin-XR for safe weight loss. Not to mention the high price of this diet pill. $80 is a lot to spend on a dietary supplement; especially when there are so many others available for much less money.
Summer Banks Dietspotlight Author
About the Author:

Summer Banks, Director of Content at Dietspotlight, has researched over 5000 weight-loss programs, pills, shakes and diet plans. Previously, she managed 15 supplement brands, worked with doctors specializing in weight loss and completed coursework in nutrition at Stanford University. full bio.

26 Fastin-XR Reviews

  • CCP

    I actually lost 20 lbs last Summer when using this. It took less than two months I’m not sure why others haven’t had the same results but people are different. What works for one person may not work for another person. I’m getting ready to order some more because I need to lose 30 more lbs in addition to what I lost last year. I’m sure this will do the trick.

    • Lashawn

      Absolutely yessssss i hadn’t even read your comment before i made mine an we said the same thing CONGRATULATIONS to you on your accomplishments😊

  • Singh

    Worst medicine I ever had side affects like heart racing so fast. Bp high and dizzy

  • Jamie

    I have taken many diet aids and I actually have a very high tolerance to any type of stimulants. When I purchased the fastin XR, I started with only one capsule to access my tolerance. After 15 minutes of taking it, I had the shakes, my heart felt like it was beating out of my chest, and I was nauseated. I have never had this reaction with any other product. I don’t recommend this product at all.

    • Montana (Editor)

      Hi Jamie. We’re sorry you had such a bad reaction to Fastin XR. You may want to check out Dietspotlight Burn. It only contains 75 mg of caffeine, which is less than what’s in a small cup of coffee!

  • Jennifer

    I have tried fastin a few times in the pass and I loved it!!! I do realize everyone body is different and you have to use what’s best for you. Also consider your health problems. Consult with your PCP. I have tried many products in the pass. Nothing have ever add up to this product. I went from a size 18/20w to a 12 when I was taking it a few years ago. I was able to wear some of my 10 year old clothes…. I just purchase fastin xr today hoping that it will work as good as fastin.

  • Ashley

    took it first three days one in morning and one in afternoon was fine no side effects ..dident feel any change 4th day took it in morning and felt my heart race got very hot and dizzy felt like I was gonna pass out and room was spinning.. told my hubby I wanted to go to ER within 2 mins of taking it.. also I felt tired and moody all day after ..

  • Victoria

    I used to take fastin/Fastin XR in 2012. Within a few short months, I went from a size 9/10 to a 4. I kept the weight off for 3 yrs after stopping this product. I’m only 5’3″, so all the extra weight on me was really noticeable. I didn’t like the side effects at all, shaking, racing heart…but it definitely worked. I just started taking this product again, a few days ago, because I’ve gained 35+ lbs within 4 months due to major lifestyle changes. I’m trying to get back on track again. Hopefully, I’ll get similar results this time around too. Rated only 4/5 stars because of side effects.

  • yanal

    RHIS PRODUCT IS BEYOND HORRIBLE !! I’ve taken adipex before and this doesn’t compare . My heart was racing I was anxious even after going to a half pill. The weight loss that doesn’t happen isn’t worth the heart attack or complications it will give !!

    • Montana (Editor)

      Hi Yanal. We’re sorry you had such adverse reactions to Faston XR. If you haven’t already, you should discontinue use immediately. You may want to try a weight loss supplement with limited side effects, like Dietspotlight Burn.

  •  Made my blood pressure high
    Samantha Gaona (Verified User)

    I took 1 tab, in the morning before work, about 15 minutes after my heart my racing. I work in a doctors office so i took my blood pressure, it was 160/92 and pulse 103. It was pretty high. I took it again at 1pm, it went down to 142/81 pulse 80. Still high. I can not focus much. it hard to sit and stare at a computer. When speaking with patients my mouth is not speaking as fast as my head. Ha anyway. They do keep me from feeling hungry. But I just dont like the affect if gives me.

  • Love this but locally not available , online its triple price !
    Bmw (Verified User)

    Love this product but have recently moved and unfortunately can not purchase locally…have looked online and the price is double sometimes triple online plus shipping.

    • Tamm

      Family OTC

  •  It works for me
    Gretchen C Gibson (Verified User)

    I’ve actually seen great results. I am down 22lbs now in less than 2 months. Yes it does give me the jitters, especially if I drink coffe before taking it. It curbs my appetite and gives me tons of energy. One thing I do suggest is that within 10-15 minutes eat something small but filling. If you do not eat anything after taking it, you will get dizzy and nauseous. Also, drink plenty of water because it gives you major cotton mouth. Start with the 45 count bottle to see how your body handles it because not everyone can take everything.

    Lauren McGuiness (Verified User)

    I only took one and it drastically raised my heart rate! A normal heart rate is 75-100 beats per minute and my heart rate is currently 144 beats per minute!

    • Lauren McGuiness

      I still have a high heart rate and it’s been an hour or so since I took ONE pill and I also threw up multiple times and I’m super dizzy and light headed if you use these make sure you are super careful!

  •  Read the bottle
    Jenna Allen (Verified User)

    Fastin works really well. Read the bottle, it has a lot of caffeine which will make your heart race. Move around and keep busy when you take it. It’ll help offset the side effect. I lost 10lbs in 16days. This stuff is great. They should put it back on the market.

  •  Stop Complaining!!!!!!!!
    Lashawn (Verified User)

    I’ve been taken Fastin Rx for bout 2 years off and on it decrease my appetite boost my energy and i have lost weight didn’t exercise or change my eating habits but dranked more water i love this product an will continue taking it i wish i could post a before and after picture to show you guys my results i have not had any side effects so to those that are complaining about this product you all are making it bad for the people that it’s actually working for why don’t you just stop taking it what works for me might not work for you and vise versa God made everyone different REMEMBER EVERYTHING AIN’T FOR EVERYBODY…………

  •  Reduces stress, controls appetite....but haven’t lost weight.
    Rita (Verified User)

    Seems to work like Phenterimine. Unfortunately in my case, it relaxes me. People with Add have the opposite side effect so instead of energy, it calms us down and reduces stress. And it really does relax me like no other ..but without making me sleepy. Perhaps it can reduce cortisol levels that contribute to belly fat. I don’t experience any jittery or increased heart rate. It also reduces my appetite so I don’t crave as much. I haven’t lost much weight with it though. Now, I just buy it because it reduces stress.

  • Donna Oyadomari

    Unfortunately this product caused me to have an allergic reaction. Please let me know how to return the unused product. I apologize for this, however, I am unable to take anymore.

    • Cameron (Editor)

      You can call this company, Donna, with the contact info we’ve provided in the Q&A section.

  • Shana

    I have tried both the 45 count and the 90 count of fastin-Xr and the 45 count seemed to work ALOT BETTER then the 90 count. I was not hungry and got full quickly. Taking 1 pill at a time instead of 2 in the morning and 1 in the afternoon worked better for me, good inc in energy without the jitters when taken that way. I bought the 90 count when I couldn’t find the 45 count anywhere and didn’t feel anything at all with them.

  •  These pills are awesome and I will definitely recommend them.
    Michelle (Verified User)

    I have been taking these pills for 3days now and not only did I get my first compliment today but I also have not been hungry since I started taking them!!!! These pills are awesome and I will definitely recommend them

    • cheryl

      I bought these pills awhile back but never gave them a try. Now that I’ve gained a whoops load of weight an extra 20 lbs!! I’ve tried clothes on and nothing fits. I’ve decided to open bottle and pray that a genie comes with them and help me to help myself. I’m so depressed. It feels like everyone looks at my big butt!! Lord knows how uncomfy I am with myself.So if you have got benefits with this product please let me know what kind of food helped out.If you have any advice my ears are open. Please share. Your new friend. Ms.Cheryl

      • Michael Palmer

        Cheryl, how are you? I know this reply has taken near a year for you to receive it, but I just want to say…Don’t Give UP! I certainly know how you feel about putting on weight. Weight gain has been my nemesis for years. Im trying these Fastin pills in hopes to curb my appetite. (Folks say they work) Since I’ve increased my cardio, Im always Hungry. I swear, there’s always something!!! Lol! but seriously, I’m not giving up and I hope you don’t either! Good Luck and stay focused!
        Mike P.

        • Samantha Gaona

          It higher your bp, and pulse. Be careful within 20 minutes of taking 1 pill my heart was racing. my bp and pulse was. 160/92 and pulse 103.