Commonly Asked Questions about Phentermine
- Why is this medication prescribed?
Phentermine is used to assist patients in losing weight, by suppressing appetite and boosting energy levels. Combined with diet and exercise, these effects may speed up your metabolism, burning more fat, increasing weight loss.
- How should this medicine be used?
Phentermine is taken once daily, in the morning, by mouth in the form of a tablet pill. Phentermine is only available by prescription. Weight Loss MD only uses pharmaceutical grade medication from manufactures in the United States.
- What is the average weight loss I should expect to see in the program?
Patients will begin losing weight right away. The average recorded weight loss per patient is about 8-12 lbs. a month.*
* No healthcare provider can guarantee results for any patient.
- How exactly does Phentermine work?
Phentermine has a primary effect on the hypothalamus, which is a part of the inner brain. The hypothalamus is the part of the brain that controls the autonomic nervous system, appetite, body temperature and sleep cycles. By affecting neurotransmitter re-uptake in this area of the brain, Phentermine effectively decreases appetite levels, suppressing the need to snack through-out the day. To effectively lose weight, one needs a diet plan that will cater to his or her own specific needs, the decrease in appetite aids the weight loss process by far.
- Is Phentermine the same as “Fen-Phen?
“Fen-Phen” was a nickname given to the weight loss drug combination of Fenfluramine and Phentermine, which were popular from about 1994 to 1997. Fenfluramine (also known as Pondomin) and the closely related Dexfenfluramine (Redux) were subsequently voluntarily removed from the U.S. market by their manufacturers, at the request of the Food and Drug Administration (FDA) due to concerns about these drugs possibly damaging heart valves in some users of these medications.
Phentermine, used without Fenfluramine, was not found to be associated with this increased incidence of heart valve changes and, therefore, was allowed to remain on the U.S. market and has remained for over 40 years.
- Does Phentermine have Ephedrine in it?
The answer would be “No.” Phentermine and Ephedrine are two separate medications. Phentermine is available only by prescription, and is not sold as part of an herbal cocktail. Ephedrine, because it is “naturally occurring” and not under “as strict” FDA control, has been used in a variety of herbal energy boosters, fat burners and dietary supplements.
- Is Phentermine addictive?
Phentermine is classified as a Schedule 4 controlled substance by the Food and Drug Administration, implying that it does have a potential abuse liability. Keep in mind, Schedule 1 being the highest and Schedule 5 being the lowest.
Over time, tolerance to the medication does develop, and due to tolerance development, the side effects caused by this medication and some of its appetite suppressant effects lessen over time, which is one common component of a potentially addictive drug.
For the vast majority of participants, no significant euphoric effect or “high” is experienced from the medication, nor does the development of “craving” for the drug appear to occur. If the drug were to be discontinued abruptly, many participants may experience some rebound hunger and rebound fatigue, but no severe withdrawal symptoms of the sort are generally associated with Phentermine.
The development of psychological dependence on Phentermine, where participants are using the medication in lieu of developing good health habits is of equal, or greater concern. This is something that we look out for and monitor within our patients, therefore aiding patients to not view Phentermine as a “crutch.” Psychological dependence is the main reason we do not recommend Phentermine use for those seeking only modest weight loss.
- What side effects does Phentermine have?
Dry mouth is the most common side effect we see, and the one side effect that lingers the longest. It is usually manageable by following common-sense measures such as drinking lots of water and chewing sugar-free gum.
Sleeplessness is the next most common side effect, presented either in the form of having a hard time falling asleep or awakening very early in the morning and not being able to get back to sleep. This occurs primarily in the first week of Phentermine use and can be considered a nuisance to some; however, for some patients it can linger for a few weeks, but will diminish gradually over time.
Constipation also occurs frequently while taking Phentermine, and can linger for some. Constipation can usually be managed by being aggressive in terms of water consumption and fiber intake.
Mild headaches, restlessness, anxiety, irritability and occasional heart racing are common with a new user starting Phentermine, but these side effects tend to subside quickly.
Other side effects are rare and usually mild when they do occur. These uncommon side effects include: dizziness with sudden standing, blurred vision, hesitancy in starting urination (in men), and occasional gastrointestinal irritation when taken on an empty stomach.
Under our program results, we list the percent of participants (of the first 500 visits, to visit #5), who are reporting symptoms thought to be “probably related” or “related” to Phentermine use. By Visit #4, about six weeks into the program, the only side effect persisting in more than 10% of participants is a dry mouth. The only symptoms persisting in more than 2% of participants are: dry mouth, sleeplessness, and constipation. As tolerance to Phentermine continues to build over weeks and months, these side effects gradually subside.
- If tolerance to Phentermine’s effects build, does Phentermine quit working after a period of time?
As tolerance to side effects build up, most participants also experience tolerance to the appetite suppressant effects of Phentermine over time. To a large extent, this tolerance development can be compensated for by gradual titration of the medication dose upwards, usually by adding a second dose in the early afternoon to continue to provide good all-day appetite control.
- Can I use Phentermine if I have high blood pressure?
A history of high blood pressure is not an exclusionary condition to use of Phentermine; however, blood pressure does need to be under adequate control (e.g., ideally systolic blood pressure <135 mm Hg and diastolic blood pressure <85 mm Hg) prior to beginning the program. We assess blood pressure at every visit, referring patients back to their primary care provider for more adequate blood pressure monitoring in the event that it does become too high.
However, as our results show, average blood pressure for participants in the program actually decreases from the first visit.
The number of patients who actually experience an increase in blood pressure as they progress through the program is quite small.
- Can I use Phentermine if I am taking a thyroid medication?
A history of hypothyroidism and use of thyroid replacement medication should not exclude participation, as long as the amount of thyroid medication a participant is taking is appropriate to what they need. Thyroid medication can produce symptoms of high blood pressure, heart racing, jitteriness, and anxiety, similar to being on a strong stimulant. Compounding this over-medicated condition with another stimulant, such as Phentermine, could exacerbate these symptoms. However, as long as this over-medicated condition was avoided, Phentermine use by someone on thyroid replacement should not be a problem.
- Can I take Phentermine if I am on an antidepressant?
This is a question that is best answered by your primary care prescribing provider or psychiatrist.
There is a class of older antidepressants called MAO inhibitors that you definitely cannot take in combination with Phentermine.
For patients on newer antidepressants, which are in more common use (e.g. Prozac, Paxil, Zoloft, Celexa, Effexor), we are not aware of any adverse interactions, and we have many patients in the program who are on these medications and remain fine. Whatever the case, your prescribing provider should still be consulted prior to starting this program.
- Can I use Phentermine if I am pregnant, may become pregnant or breast-feeding?
Although Phentermine has not been associated with birth defects in any animal studies, we advise women who are pregnant or planning to become pregnant to not take Phentermine. As Phentermine can show up in breast milk, we also advise that Phentermine should not be used by women who are breast-feeding.
- What over-the-counter medications should I avoid if I am taking Phentermine?
For those taking Phentermine, we advise caution in the use of over-the-counter stimulant medications, primarily decongestants (Pseudoephedrine) and caffeine. If a decongestant must be used, we recommend that the participant have his or her blood pressure checked several times while on this product.
We also recommend that all products containing the drug Ephedrine be avoided. The long list of products that contain Ephedrine, include various energy boosters, fat burners and various diet supplements.
- How often and when should I take Phentermine?
When starting Phentermine, once per day dosing is usually adequate for good all-day hunger control. We usually recommend taking the Phentermine at about 9 or 10 AM, so that it has taken effect by lunchtime, lasts through dinner, and yet still wears off by bedtime to allow for sleep.
- What dose of Phentermine do you prescribe?
Unless otherwise indicated by the participant’s past medical history, a single 37.5-milligram pill, taken once per day, is a usual starting dose. On return visits, this dose may need to be adjusted up (for persisting hunger) or down (for persisting side effects) depending on the participant’s response.
- Do I need to worry about being on Phentermine if I get drug tested?
There are some professions, such as commercial airline pilot, where taking Phentermine (as with many medications) is not allowed. In most other cases, having a letter from our program stating that a participant is receiving this medication as part of a physician-supervised weight loss program has been sufficient. Because of its similar chemical structure, Phentermine could produce a false-positive result for Amphetamine-like drugs on a broad screen immunoassay, such as a urine-tox screen. However, a follow-up test, which is more specific, such as Gas Chromatography, should clarify that the drug is Phentermine and not an illicit substance. However, showing an employer our letter before any drug testing has occurred should prevent this from becoming an issue. If you have additional concerns you should follow-up with your employer.
- On days that I have forgotten to take Phentermine, I am still not hungry. Why is that?
Phentermine takes about three to five days to build up in the system (to what is called a “steady state”, which is why some people report not feeling its full effect until being on it for several days.)
Phentermine also takes about three to five days to “wash out” of the blood, therefore, if a day is missed, there is still quite a bit left in the system. Although, forgetting a day here or there appears to have little effect, we have still found that the participants that do the best at losing weight on Phentermine, tend to be those who are regular in taking their prescribed doses every day.
- What happens when I quit taking Phentermine?
If you were to quit taking Phentermine abruptly, you would likely experience some rebound hunger and rebound fatigue, and there could be some weight gain associated with the termination of Phentermine.
Unless you have significant side effects from Phentermine, or a prescribing provider has advised you to discontinue it, we do not recommend stopping Phentermine abruptly. We recommend weaning down off of Phentermine over a period of time, even after achieving your target weight. Weaning yourself off of Phentermine can help to avoid an abrupt transition.
- Will my hunger return and my weight come back when I quit taking Phentermine?
From patient reports, it appears that for most participants, hunger does not jump back to its previous level within the first few weeks or months of ending your Phentermine intake. The typical pattern after discontinuing Phentermine, is that diet and physical activity are well-maintained for several months to years. Studies suggest that subsequent weight regain, if it does occur, is usually precipitated by an injury or severe environmental stressors which disrupt the maintenance routine.
- Is there any way of telling how I will respond to Phentermine, other than by trying it?
A very rough indicator would be to examine how you respond to other stimulant medications, such as caffeine, and over-the-counter decongestants before taking Phentermine.
If you are extremely sensitive to these products, you may only need a very low dose of Phentermine for it to be effective, which will aid in avoiding side effects such as sleeplessness, jitteriness, and heart racing.
If you are highly tolerant to stimulants, you may still be hungry on a standard Phentermine dose, and it may have to be increased to produce adequate hunger control.
Another rough indicator is to examine how close blood relatives (i.e., brother, sister) have responded to Phentermine, since close relatives often appear to be quite similar in terms of their tolerance levels.
However, these are only very rough guidelines, and the only definitive test of how you will respond is to actually try it, under a prescribing provider supervision. (Interestingly, starting body size does not appear to be a big predictor of initial response to Phentermine, with some relatively large individuals responding to small Phentermine doses and vice versa.)
- Do you recommend buying Phentermine over the Internet?
If you are buying Phentermine from a reputable source in the U.S., such as Walgreens.com, that requires your prescribing provider prescription, you can probably safely assume that you are getting a legitimate product.
On the other hand, if you are ordering a product from a location with no visible address or an overseas address, or from a website which dispenses Phentermine based on an “online consult,” aside from legal issues, you may be taking a very real chance that the product you receive is not the real thing. We have spoken with several participants in our clinic who reported side effects from “Phentermine” bought off of the Internet, that led us to suspect that what they received was not in fact Phentermine. We highly advise against any internet purchasing of Phentermine from any of the three places described.
- What is the average weight loss I should expect to see on the program?
As our program is intended for the development of permanent healthy behaviors and not for acute dramatic weight loss, we advise patients complying with the program to anticipate an average weight loss of 1 to 2 pounds per week, or roughly 1% of their body weight per week, which is considered to be an optimum amount to preserve muscle mass while burning fat. With this plan, the transition to the weight maintenance phase of the program is then a very smooth process where the diet and exercise habits remain the same as those of the weight loss phase.