Phentermine is a prescription appetite suppressant used for the short-term treatment of obesity. It is utilized along-side behavioral changes like healthier diet and regular exercise to promote weight loss.
Phentermine hydrochloride (phentermine HCL) is a Schedule IV drug under the United States’ Controlled Substances Act and the international Convention on Psychotropic Substances.
This medication is a sympathomimetic amine anorectic and functions as a central nervous system (CNS) stimulant. Its active ingredient, phentermine hydrochloride, promotes a stress response similar to the “fight or flight” reaction generated during times of stress, thereby reducing appetite and increasing energy to promote faster weight loss.
Phentermine can produce a wide variety of side effects. Serious potential side effects include heart and lung problems. However, most people only experience minor reactions. The most common side effects of this medication include dry mouth (xerostomia), trouble sleeping (insomnia), constipation and headache.
Skip to the Side Effects section to learn more about side effects.
Phentermine resin was first approved by the FDA in 1959, and the medication’s current form (phentermine HCL) has been available since 1973.
In the early the 1990s, Dr. Michael Weintraub and his colleagues at the University of Rochester published a paper detailing the effectiveness of an off-label combination of fenfluramine and phentermine for weight loss. This cocktail was commonly known as “Fen-Phen” and doctors regularly prescribed the two medications together. However, in 1997 a group of Mayo Clinic physicians published findings that the powerful combination increased patients’ risk of heart valve disease. Fenfluramine, the culpable substance, was voluntarily withdrawn soon thereafter. Phentermine has remained available for prescription and sale.
Phentermine helps you lose weight by suppressing appetite and boosting energy.
At its most basic, weight loss is a matter of creating an energy deficit: averaging more calories burned than calories consumed. This medication helps you eat less and move more, which leads to a greater energy deficit and more weight loss. It achieves these effects by acting as a central nervous system stimulant.
Phentermine boosts your weight loss efforts, but it’s still up to you to eat well, incorporate doctor-approved physical activity and make healthy lifestyle choices. Committing to sustainable behavioral changes will not only maximize weight loss with phentermine, but also help you keep the weight off after your prescription comes to an end!
Phentermine diet pills have one active ingredient: phentermine. Most pills contain phentermine HCL. Ionamin contains phentermine resin.
Phentermine HCL is a sympathomimetic amine, which has a chemical structure similar to amphetamines. However, phentermine is NOT an amphetamine.
Different forms (capsules, tablets, etc.) and brands contain distinct inactive ingredients. These inactive ingredients include fillers, dyes and binding agents.
Patients with a BMI ≥30 kg/m2, or a BMI ≥ 27 kg/m2 in the presence of another weight-related condition, may be eligible for prescription weight loss medication.
Phentermine is designed as an adjunct treatment for generally-healthy overweight or obese patients who have not lost sufficient weight using diet and exercise alone. For this reason, this medication is specifically prescribed for the treatment for exogenous obesity (or overweight), which is obesity caused by external factors like eating too much or exercising too little.
Phentermine is not appropriate or safe for everyone. It’s critical that you inform your doctor of all current and past medical conditions, as well as any current or recent medications and supplements. Taking this medicine in the presence of certain medical conditions, or in combination with specific medications, can prove extremely dangerous.
→For a more comprehensive list of precautions and contraindications, please click here.
REMINDER: Only a medical doctor can evaluate if phentermine is appropriate and safe for you.
Phentermine produces a variety of side effects. These reactions range from relatively mild to very severe.
While most patients take this mediation without issue, phentermine can cause serious side effects. These reactions include potentially-fatal heart and lung problems.
Call emergency services or contact your doctor immediately if you experience any of the following reactions:
→For a more comprehensive list of phentermine side effects, please click here.
Thankfully, most patients experience only minor to moderate side effects.
The most common side effects of phentermine are dry mouth (xerostomia), trouble sleeping (insomnia), constipation and headache. Other widespread reactions include: change in sexual desire, diarrhea, dizziness, mood changes (e.g. “phen rage”), nausea or vomiting, rapid (racing) heartbeat, rash, stomach pain, tiredness, and unpleasant mouth taste.
Below are the results of a forum poll to assess the incidence of common side effects:
Phentermine is available in doses ranging from 8mg to 37.5mgin most countries.
These distinct quantities of medication can be taken anywhere from one to three times per day, depending on your doctor’s instructions. Both the individual dose and frequency of use determine your daily dosage.
The recommended maximum dosage is37.5 milligramsper day.
The strength of a particular pill is determined by how many milligrams of phentermine HCL it contains. Popular phentermine doses include:
In Australia and South Africa, it’s also possible to purchase Duromine, which comes in a maximum dose of 40mg.
Adipex, formally known as Adipex-P, is the most popular brand of phentermine in the United States.
This medication contains phentermine HCL as its main ingredient. It is manufactured by GATE pharmaceuticals and available as either tablets or capsules – both providing a 37.5mg dose. Adipex-P is typically taken once per day, either before breakfast or 1-2 hours after breakfast. However, in some cases it may be preferable to split the Adipex tablet in half and take two smaller doses instead.
This is what Adipex capsules and tablets look like:
Apipex-P blue and white capsules 37.5 mg Adipex tablets
Adipex (or Adipex-P) is a specific brand of weight loss pills, while “phentermine” refers to all generic and brand name products with the single active ingredient of phentermine.
Adipex is the most popular brand of phentermine in the United States. Phentermine also sometimes refers specifically to the medication’s active ingredient (phentermine HCL) as opposed to the medication as a whole.
Lomaira is a low-dose brand of phentermine weight loss pills.
This medication is manufactured by KVK Tech. Lomaira provides the lowest-available dose of at just 8mg per pill. Since it can be taken up to three times per day, Lomaira is popular for patients who do not tolerate higher doses, or for people that struggle with nighttime cravings.
This is what Lomaira tablets look like:
Qsymia is a combination of topiramate extended-release (brand name: Topamax) and phentermine HCL.
Despite its relatively-recent FDA approval, Qsymia is very popular. It differs from other pills because it contains more than one active ingredient. While phentermine works to suppress appetite and boost energy, topiramate fights cravings by making food seem less appealing. Qsymia comes in four different doses (all capsules) that can be used progressively. One benefit of this brand/combination is that it is approved for a longer period of use than phentermine alone. Qsymia is manufactured by VIVUS, Inc.
This is what the different doses of Qsymia look like:
Phentermine is sometimes prescribed in combination with a low dose of topiramate as a generic substitute for the brand name medication Qsymia.
Phentermine suppresses appetite and boosts energy, while topiramate fights cravings. Qsymia has proven effective in clinical trials and can be taken more chronically than traditional phentermine.
You should never combine ANY medication or supplement with phentermine without your prescribing doctor’s EXPLICIT approval to do so.
Phentermine is an oral medication that comes in three forms:
Generic phentermine weight loss pills are available in capsule and tablet form. Brand name capsules and tablets are manufactured by several different pharmaceutical companies. Suprenza is the only ODT version of phentermine. There is no generic ODT at this time.
The most common phentermine tablets are white, oblong pills with blue specks. Below are photos of popular tablets:
Phentermine capsules come in a variety of colors. Here are some of the most common caspules:
Suprenza is the only-available ODT preparation of phentermine weight loss pills. Here’s what it looks like:
This medication is most-often taken once per day in the morning, either on an empty stomach or 1-2 hours after breakfast.
Depending on your doctor’s orders, you may take a pill anywhere from 1-3 times per day. The total intake of phentermine in one day should never exceed 37.5mg (or 40mg, if taking Duromine).
Phentermine should always be taken EXACTLY as prescribed by your doctor. Follow the directions on the medication’s label. Never change your schedule or dosage without your prescribing doctor’s approval.
If you take your capsule or tablet once per day, take it around breakfast time. Some brands recommend taking it on an empty stomach before eating, while others suggest swallowing the pill about 2 hours after eating. Suprenza (ODT) can be taken either with without meals.
It is advisable to take your phentermine early in the morning because:
If you are taking phentermine multiple times per day, precisely follow your doctor and pharmacist’s directions regarding dose and schedule.
This medication can be taken for up to 12 weeks (3 months) at a time.
Phentermine is considered a short-term medication because the FDA clinical trials only lasted for 12 weeks. Therefore, the suggested prescribing period is no more than 3 months at a time. This recommendation is supported by evidence that the active ingredient is habit-forming and taking it for too long (or using too much) can result in addiction. As a result, doctors should only prescribe phentermine for a few weeks (3 months) at a time.
Abrupt cessation can produce withdrawal symptoms.
Phentermine is a strong medication and it has a chemical structure similar to amphetamines. As a result, it can prove habit-forming. People who take high doses, or those who stay on this medication for more than a few weeks, are especially at-risk for addiction.
Due to the medication’s potency and chemical structure, withdrawal symptoms can occur when you stop taking phentermine.
Some potential withdrawal reactions include:
If you recently stopped phentermine and are currently experiencing any of these symptoms, contact your prescribing doctor for advice and assistance.
To minimize the risk of these responses, speak with your doctor about gradually decreasing your dosage (instead of stopping the medication abruptly).
Due to an increased risk of seizures, Qsymia should not be stopped abruptly unless under direct medical supervision. If a Qsymia prescription is discontinued, the patient should gradually wean off the medication to reduce this risk.
Many people find themselves searching for continued appetite suppression after their prescription runs out. Since phentermine should only be taken for a few weeks at a time, some patients seek-out a more long-term option.
Phen Caps is a dietary supplement that helps suppress appetite and boost energy. It does NOT contain any phentermine HCL, but instead relies on nine natural ingredients to help achieve these objectives. Phen Caps are an effective and natural appetite suppressant with positive customer reviews and a 100% satisfaction guarantee. Phen Caps are only available online at phen.com.
No, phentermine is NOT an amphetamine.
However, the two drugs do possess a similar chemical structure. As you can see in the image below, the only difference between the two substances is the methyl group (CH3) on the phentermine methyl, which takes the place of the single hydrogen (H) atom in amphetamine.
Like amphetamines, phentermine works by stimulating your central nervous system. This makes it highly effective for promoting weight loss, but also makes it potentially-addictive and dangerous if not used as directed. However, phentermine is a Schedule IV drug while most amphetamines are Schedule II, which indicates prescription medication’s lower addictive potential and medically-recognized use.
Due to the structural similarities, phentermine may show-up as a false-positive for amphetamines on standard drug screens. Therefore, it is critical that you provide a valid doctor’s prescription if you are requested to undergo drug testing.
It may. Given the similar chemical structures between phentermine and amphetamines, the medication sometimes shows up as a false-positive for amphetamines on a urine drug test.
Phentermine is legal when used for weight loss under a doctor’s supervision, but you should always be prepared to show a current and valid prescription. With more specific testing it is possible to distinguish between the prescription medicine and other [illegal] drugs.
The half-life of phentermine HCL is 16-31 hours, so most people would not test positive for the chemical after 4-7 days without use. However, this time period varies from person-to-person. Some of the factors that may influence how long the medication stays in your system include: urinary pH, duration of use and daily dosage.
Given that the active ingredient is a controlled substance, it is illegal to take phentermine without a valid doctor’s prescription.
Phentermine is a prescription-only medication, so you can only purchase it with a valid doctor’s script.
A licensed physician – either your primary care physician (PCP, GP) or a weight loss specialist can write the prescription. He or she will assess your medical history, current and recent medications & supplements, health and weight status to determine if this medication is right for you.
You cannot buy phentermine without a prescription.
If you do not qualify for prescription weight loss medication, speak with your doctor about other options to help you lose weight. He or she may suggest that you:
If you’re interested in OTC supplements that you can buy online & without a prescription, consider Phen Caps – a natural appetite suppressant.
You can fill a valid prescription online with verified online pharmacies. Visit your preferred pharmacy’s website to learn more about their specific requirements and instructions.
If you want to buy online but do not have a prescription, you can buy an OTC appetite suppressant instead. Phentermine.com recommends Phen Caps – an all-natural dietary supplement that reduces appetite and boosts energy.
You can buy Phen Caps online here.
The cost of weight loss medication varies widely depending on whether you purchase generic or brand-name pills, as well as your insurance coverage.
The table below details estimated costs for a 30-day supply of phentermine without insurance. As you will notice, cost varies drastically between generic & brand name, as well as between more simple versus more complex preparations.
All of these prices were sourced online and are for informational purposes only. They do not represent any sort of price guarantee or coupon. However, many manufacturers’ sites do offer online coupons to bring the cost of the medication down if your insurance does not cover the cost of treatment.
|Brand||Estimated Cash Price for 30-Day Supply*|
|Adipex||Tablets (37.5mg)||$67 - 76|
|Capsules (37.5mg)||$13 - 57|
|Generic||Tablets (37.5mg)||$9 - 19|
|Capsules (15mg)||$13 -27|
|Capsules (30mg)||$13 - 26|
|Capsules (37.5mg)||$11 - 28|
|Qsymia||Capsules (3.75mg / 23mg)||$185 - 205|
|Capsules (7.5 mg / 46 mg)||$190 - 210|
|Capsules (11.25 mg / 69 mg)||$205 - 225|
|Capsules (15 mg / 92 mg)||$205 - 225|
|Suprenza||ODT (15mg)||$225 - 245|
|ODT (30mg)||$225 - 245|
|ODT (37.5mg)||$225 - 245|
|Lomaira||Tablets (8mg)||$26 - 54|
* Prices updated in April 2018. Displayed in US dollars (USD). Estimated price before insurance, coupons or discounts.
No, phentermine is a prescription medication.
If you’re interested in OTC supplements that you can buy online & without a prescription, consider our favorite natural appetite suppressant – Phen Caps
Phentermine was initially approved for the Canadian market but was later withdrawn due to safety concerns. The last available brand (Ionamin) was removed from market in 2007.
Similar to the United States, phentermine is a prescription medication in Mexico and can only be legally obtained with a doctor’s prescription. You can fill a valid phentermine prescription at most major pharmacies.
Common brands in Mexico include Acxion, Terfamex and Raamcap, in addition to generic preparations.
Yes, this medication is widely available in Chile.
In fact: phentermine sales have exploded in Chile in recent years, going from less than 4,000 boxes in 2012 to almost 1,000,000 boxes in 2017 – just five years later! To purchase this medicine in Chile, you’ll need a valid “receta cheque” from a medical doctor. You can then fill this prescription at most major pharmacies.
Common brands available in Chile include Compulxine, Elvenir, Finapet, Obexol and Sentis, in addition to generic preparations.
Prescription appetite suppressants are not available from the NHS but are still offered by some private slimming clinics.
Stimulant-based appetite suppressants were withdrawn from the market following the European Medicines Agency’s 2000 decision to ban such substances throughout the EU. Following this ruling, the only prescription weight loss medications available through the NHS are Xenical or Alli. These pills both contain orlistat as the active ingredient and work by decreasing the absorption of dietary fat in one’s GI tract.
Phentermine and diethylpropion are still available, however, from some private slimming clinics.
In 2000, the European Medicines Agency ruled to ban prescription appetite suppressants sales across the region. The agency’s recommendation to remove phentermine from the market was based on concerns about patient safety and potential addiction or abuse. Several countries that had previously permitted the prescription/sale of phentermine withdrew the medication from market following this decision.
Alternatives include other prescription weight loss drugs or OTC weight loss supplements.
Prescription weight loss drugs are a huge market in the US, and only expected to grow. Some of the other popular prescription weight loss medications include:
Here’s more about each of those alternative prescription weight loss drugs:
Many companies produce weight loss supplements meant to suppress appetite and boost energy. Supplements are not as heavily regulated and are not approved by FDA. As a result, you should be cautious when ordering dietary supplements. Remember: phentermine is not available without a prescription, so if you see a site claiming to sell this medication without a prescription, you are likely looking at a supplement.
Among the many options available for weight loss supplements, we recommend Phen Caps. Phen Caps are an all-natural supplement formulated with nine natural ingredients to suppress appetite and boost energy.
Results vary drastically from person to person, but many people lose an average of 1-4 pounds per week while taking this medication.
It is impossible to predict exactly how much weight you’ll lose with phentermine given significant individual differences. However, based on users’ reports in the forum and Success Stories, you may expect to lose anywhere from 1-4 pounds per week. Many patients lose more weight during the first month of their prescription, and then experience a more gradual decrease in weight in the following months. Results are also highly-dependent on users’ personal commitment to lifestyle changes like healthy diet, regular (doctor-approved) exercise and stress management.
While fast, dramatic weight loss may seem appealing in theory, it is actually healthier and more sustainable to lose a more moderate 1-2 pounds per week. With slower weight loss, you’re helping your body adjust to its smaller self and minimizing damage that could otherwise be done by dramatically reducing weight in a short amount of time.
The best meal plan is a healthy, balanced diet that you can sustain over the long-term.
Unless your doctor has specifically told you differently, you should eat at least 1200 calories per day if you’re a woman, or 1500 calories per day if you’re a man. These are minimum calorie requirements to sustain basic function and prevent your body from going into starvation mode.
Looking for some more specific tips for what to eat while taking phentermine? Click here!
This medicine is designed as a temporary add-on treatment to improve the results achieved through behavioral changes, so you should aim to incorporate fitness into your daily routine.
Always follow your doctor’s orders regarding physical activity. If you have not been exercising regularly or have any doubts, make sure to clear any new workout routine with your doctor.
Experts recommend a combination of cardiovascular (aerobic), strength, flexibility and balance exercises to promote overall fitness. You should aim for 75 minutes per week of vigorous aerobic activity (e.g. running, swimming, etc.) or 150 minutes per week of moderate aerobic activity (e.g. walking, biking, etc.). This comes down to about 25 minutes 3x per week of exercises like running OR 30 minutes 5x per week of exercises like walking.
The best way to naturally increase weight loss is through the implementation of healthy habits.
After a couple of weeks or months, many people find that the medication’s effects start to fade. Understandably then, that lots of us wonder how to boost results. The best way to achieve this goal is through practicing healthy habits like staying active and getting enough sleep.
However, if you feel like your medication is no longer working, bring it up to your prescribing doctor. This may indicate that you’ve developed a tolerance to phentermine. In that case, you should take a break from the weight loss pills.
NEVER take more phentermine, or take the pills more often, than your doctor ordered.Doing so will not increase effectiveness and can prove very dangerous.
Boost your weight loss with the following tips:
Want to see real success stories from actual people?
Our Success Stories section features past & present phentermine users’ motivational pictures and stories! They talk about their motivations, challenges, victories and accomplishments to inspire and prepare you for your weight loss journey!
Here are two inspiring success stories:
Chandra: 216 pounds to 142 pounds
Brandon: from 320 pounds to 170 pounds
For more phentermine success stories, check out our Success Stories section here!
If you’re curious about how past & present users felt about their experience with phentermine, watch this short video to find out!
Interested in how real patients rate their experience on this medication? Below you will find hundreds of users’ ratings and comments about generic pills, Qsymia, Adipex and more! To see dozens more reviews, please visit our phentermine reviews page.
Weight loss is as much a mental challenge as it is a physical one. Through the ups and downs of weight loss – both emotionally and on the scale – it can prove a struggle to remain devoted. Still, research shows that those who stay committed to their weight loss journey long-term enjoy the highest rates of long-term success.
Peers play an especially important role in helping us stay motivated and accountable. A study from University of Pittsburgh School of Medicine found that individuals who embark on a weight loss journey with friends or family are significantly more likely to achieve and maintain their goal weight. This beneficial social support can either come in-person from a friend, spouse or coworker, or from a new online friend. Many people choose to keep their phentermine use a secret, so online support groups and forums play a major role in providing support for many patients.
Below you will find descriptions and links for our supportive, informative and lively online communities and support groups. Check them out and join today!
The forum is a place for future, past & present users to share questions, experiences and advice with one another. The forum has over 88,500 members and one million posts to address your everyday phentermine questions.
Here’s a snapshot of some the forum’s most recent activity:
Our official Facebook page is your source for all things phentermine! We share weekly updates to the blog, current users’ daily menus & routines, weight loss tips and connect you with our Phentermine Ambassadors.
Losing Weight with Phentermine is our official Facebook support group in English. More than 7,000 users log-in daily to ask questions, share tips & tricks and support each other in their weight loss journeys!
Grupo Oficial de Apoyo de la Fentermina is our official Facebook support group in Spanish. Each day, more than 5,000 real phentermine users from all over the world log-in to ask questions, share practical advice and support each other in their weight loss journeys!