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This Phentermine diet pill claims to boost metabolism and suppress appetite.

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  • Established: 1959 FDA approval; available in the 1970s; removed from the market voluntarily in 1997 but still available
  • Founder: Originally sold by King Pharmaceuticals; currently made by several companies
  • Accessibility: Prescription only
  • Diet Type: Appetite suppressant to be taken short-term
  • Gender: Male and female

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In December of 1998, the pharmaceutical giant, SmithKline Beecham withdrew Fastin from the market because of side effects associated with this weight loss supplement. Today, it is back on the market, as it tries to help those who are obese lose weight. Phenylethylamine, or Phentermine, is the main ingredient in Fastin. This chemical is a powerful stimulant that boosts metabolism, suppresses appetite and raises heart rate.

Fastin should only be used by people who are extremely overweight or obese and have not been able to lose weight with just diet and exercise. Fastin should only be taken under the supervision of your doctor. It should also be taken in conjunction with a reduced-calorie diet and a consistent exercise plan that has been laid out for you by your medical doctor or registered dietitian.

Fastin contains stimulants that may cause side effects like increased heart rate, shakiness or heart palpitations.

  • Fastin may help to kick off a weight loss program
  • May help to reduce weight when used in combination with a low calorie diet and exercise plan
  • Fastin was pulled off the market in 1998
  • Not a long-term solution to weight loss
  • Can induce many dangerous side effects
  • Should not be taken by certain individuals who have current health conditions
  • Should not be used for longer than a few weeks
  • Can result in dependence
  • Automatically enrolled in the auto-shipment program after registering for free trial

Fastin contains Phenylethylamine HCL, R-Beta-Methylphenylethylamine. methylphenylethylamine tartrate , methylsynephrine HCL , N-Methyl-phenylethylamine HCL, Synephrine HCL, Theobromine Anhydrous, Yohimbine HCL and caffeine.


Given the powerful effects of Fastin, it should only be taken according to the directions of your medical doctor.

Fastin is typically taken once a day 1 hour before breakfast or as directed by your doctor. Since it contains stimulants, you should not take it before going to sleep. Also, Fastin should only be used for a few weeks since it has the ability to result in dependence.


While taking Fastin, you will also be following a reduced-calorie diet comprised of 1,200 – 1,500 calories a day and a consistent exercise program that is laid out by your health practitioner. You should avoid alcohol, caffeine and any other stimulants.


Fastin is a stimulant that works in a similar way as amphetamine. In addition to being an appetite suppressant it is also a mood-elevator. Fastin should only be used by people who are obese and under the supervision of their medical doctor.

It is not recommended for use by individuals at risk for diabetes, high cholesterol levels, high blood pressure, a malfunctioning thyroid, hardening of the arteries, or heart disease or if certain medications are being taken.

Common MisspellingsCommon Misspellings

Fasten, Fastin Diet Pills, Phentremine, Phentermine, fentermine, Adipex-P, Ionamin, Obenix, Oby-Cap, Teramine, Zantryl

How Does Fastin Compare?
  • Product Name
  • User Rating
  • Has Good Appetite Suppressant
  • Has Only Natural Components
  • Contains No Coffee
  • Fastin
  • /100
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(Page 2 of 2, 38 total comments)


Went off of it for awhile because a sudden health problem. I have MS now. It causes horrid mind numbing fatigue. I take these pills now to combat the fatigue and they work great. Cleared it with my doc and I still have 45 pounds to go. Like the review said THIS IS NOT FOR PEOPLE LESS THAN 50 POUNDS OVERWEIGHT. This is very powerful and can mess with you if you are not truly fat. Dont be stupid on these pills. Only take them if you truly are ready for the side effects.

posted Jun 7th, 2011 1:31 pm user comment


My Friend tried Fastin What she don't like about FASTIN is the 100mg of caffeine. It gives her a headache. So she switched to RVL it is all natural and contains 8 vegies. She had so much energy and felt good. She slept better at night and lost 20 lbs in 4 weeks. RVL is a nutrition shake and supplements for your health. Go to and read more about it. My friends have all lost more weight this time then any other diet pill.

posted May 17th, 2011 3:40 pm

bryan p.


This is what weve been looking for

posted Apr 10th, 2011 10:42 pm


Took my first pill about 30 - 45 minutes ago and suddenly feeling cold - slightly shakey but not like i have with other pills.

I dont need to lose weight per say but decided to try this pill since I have gained since last summer and I would like to lose what I gained (about 8 - 10 lbs).

I will likely take 1 pill every morning & see what happens.

posted Mar 30th, 2011 10:08 am


Checking back in... I hate when people say they will do that and they dont. So here goes. I started at 219 and got down to 215 with the first box. Took a week off then got a second box. Just finished that box. Went from 215 to 211. Its a good pill but I think its starting to mess with my chemistry since I am on Byetta also. This is a diabetes medicine that is made of gila monster venom.... Well like I said before, this is not a pill to take if you want to lose 20 pounds or less. It makes you too woosey and lightheaded for it to be for the smaller people.

posted Nov 22nd, 2010 2:12 pm user comment


i liked it it dont really curve your appetite, but the energy is enzane, i felt untouchable wen i was on it and happy, i weighed around 240 pounds when i first started taking it and this was my first diet pill i have tooked instead of taking one in the morning and one in the afternoon i took two at once then started working out then when i felt tired i would take another one so i took three a day which probably wasnt to safe, i used about five bottles of it and i only dropped like 5 pounds so i was down 230 i stopped taking it becasue i started feeling addicted to it and i didint want to get to deep into it. then i took hydroxycut hardocre and didnt really lose anyweight but i was working out probably 6 to 8 hours a day so i was probably puttin on alot of muscle and buring fat. Then i changed my mind about losing weight, i just wanted to turn all my fat into muscle so then i stoped wanting to supress my appetite and dieting and just bulk up. Then my cousin terry told me about nitric oxide products and told about superpump 250 and jack 3d and i started to take them and i hadnt changed anything about my workout plan i just took it and workout nothing different and i started dropping pounds like crazy and was eating normaly i guess i worked out so much i built a high metabolism to burn fat off and lose wieght so i weigh about 190 now and am 6,1 and i lost all that weight without trying and when i was trying i couldnt lose any weight i guess it takes time

posted Nov 18th, 2010 5:33 am



I started Fastin two weeks ago. What I have learned is that one pill in the am and then one pill at noon is just fine for me. Two pills in the morning....well it cleans you out in a very unpleasant way. It made me slightly lightheaded and happy. Kind of like when I take vicodin for migraines. Anyway, I really didnt notice any appetite loss per se. My stomach didnt growl as much, but I still ate the same. The reason I started this is because I have worked out everyday for 5 months straight (after 15 years of being lazy) and dropped 4 sizes but only one pound. I wanted the scale to budge. I already work out eat right and drink 6 liters of water a day. I just needed a slight kick. After two weeks I lost 6 pounds. I just bought another box and I plan on taking it til its gone then taking a week off. I'll keep doing that til I hit my goal weight. That is if I do not suffer any ill effects. I am diabetic and do not feel the need to kill myself. I do NOT think this pill is for anyone wanting to lose 20 pounds or less.

posted Nov 15th, 2010 7:08 pm user comment


I am starting this in the morning. We shall see! I need to lose a bunch of weight! I am 5'6 and 400 lbs. I have been trying all my life to lose weight! I hope this works! I will keep you posted.

posted Nov 2nd, 2010 8:39 pm


I begin taking Fastin and within one week, I have lost 12pds. I eliminate breads, sugar, soda, and dairy products. I workout 3x a day and a brisk walk on Sunday. I only take one pill for the entire day and it really works!!!!!

posted Nov 2nd, 2010 6:54 pm



hi all, i started fastin on OCT 12, 2010 i took a pill that morning at 7:10am w/o food and it was ok gave me energy w/o appitite supress.. i took another one at 11:40 am and ole boie my heart went to racing like crazy and i could feel my self shaking and it took away my appitite i would give it a 6 appitite supress and 22 energy. i ate less calories today. am 5'2 and 205 pds my normal calories i eat was around 2600 and today i ate 1000 ok i am waiting on this pill to mess up but it's only been 2 days doing good so far... today i took 1 pill at 7am again and it had my heart racing like crazy but lite shaking (first day was worst with the shaking) and ole boie my appitite was suprres i try to eat a bowl of cabbage soup i made today and couldn't eat. i drink 40z of water then try to eat my soup only ate 3 table spoons after that i couldn't go any more i almost throw up.... today my calorie intake around 950 calories.... i'm not gone to weight my self yet not until a seven days... so far so good +

posted Oct 14th, 2010 5:11 pm


today OCT 8 2010 i buy fastin at gnc for 44.00 bucks. i heard alot about fastin and will give it a try but i want start not until OCT 11 2010. my weght now is 5'2 205 pds yes i am over weight and need to lose it quickly... hey I also wants to try fastin with NATURALCARE APPITITE SURPRESSANT since it dont have any caffine or other stimulants in it.. can i try both together anyone.... i think both really would surpress my appitite and get the energy from fastin....... WHAT U THINK......

posted Oct 8th, 2010 10:04 pm



i just started taking this pill and i have to agree with layla i took when i woke up and was hungry and almost imediately my hunger was gone the only thing i don;t like about it is the taste and the texture of the pill itself other than that its workin great so far

posted Aug 25th, 2010 1:03 pm



That fastin from GNC is not the real thing. It is designed to give u sorta of the same feel but its not the same thing... The real fastin cannot be given without a Rx. One major difference between the two are that the real one can only be taken in the morning an hour before u eat or else it will keep u up all night. The GNC version u take twice daily... Another difference is that the real Fastin contains Phentermine. GNCs version contains Phenylethylamine HCL and Caffeine

posted Jun 19th, 2009 2:52 am



Fasten IS available at GNC. I have only been on it for a few days, but it is the closest I have come to finding something that gave me the same energy and appetite suppression as ephedra stackers. I am 5 ft. tall and 135 lbs. and I am here to say, only take one in the morning, not 2 because 2 is too much. It hits your system almost immediately. Good stuff, hope it helps me lose some of this extra weight.

posted Mar 2nd, 2009 9:56 am



You know you can buy FASTIN at GNC. Someone mentioned a prescription but you don't have to have one. What I don't like about FASTIN is the 100mg of caffeine. It gives me headaches. Has anyone experienced this and have any advice for dealing with the headaches?

posted Jan 2nd, 2009 10:22 am



I loved this diet pill, out of all the ones I have tried over the years this and adipex are the best. I completely agree with Layla it is great and it is a little costly as $70 a bottle but well worth it.

posted Dec 4th, 2008 2:13 pm



I have tried this pill. When i first started taking the pill its effects were really strong. Its an appetite suppressant and my appetite the first few days was almost nonexistent. After that the effects get noticeably weaker but it still works. I found myself getting fuller after eating less. Also during the first few days i had so much more energy. My doctor warned me that it may raise my blood pressure and cause insomnia (you will have insomnia if you take it too late in the day) but i had none of that. I took one pill every morning and usually felt hungry enough to eat something six hours later. My biggest complaints about this pill is that the effectiveness wears off the more you use it and that it is a short term pill. My doctor said i could use it for two months and then wait one month before i could get another prescription because its effectiveness would completely disappear with regular use. What i love about it the most is that my appetite and hunger are reduced and it has replaced my need for coffee in the morning. I sleep about 5 hours a night but when i take this pill my yawning and sleepiness are eliminated.

This pill may not be appropriate for everyone. My doctor was surprised at how i saw little to none side effects. You should speak with your doctor to see if it's right for you.

posted Nov 23rd, 2008 12:58 am



has anyone tried this? i want to know if anybody tried this ........!! thanks

posted Nov 9th, 2008 1:20 pm


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