FDA-Approved · 65+ Years of Clinical Use
Fast-acting. Medically supervised. A proven prescription option for weight loss.
Phentermine has been used in medical weight management for decades. At Rivas, we prescribe it selectively, monitor your progress closely, and adjust your plan based on your results and tolerability.
PRICING
Get started with phentermine
Every visit includes a provider visit, vitals and weigh-in, and medication. No separate pharmacy trip required.
Initial Visit
$195
Provider visit + first 2 weeks of medication included
2-Week Follow-Up
From
$90
Provider visit + vitals and weigh-in + 2 weeks of medication included
Monthly Follow-Up
From
$115
Provider visit + vitals and weigh-in + 4 weeks of medication included
HSA & FSA accepted. Follow-up pricing may vary based on dose and treatment plan. View full pricing →
HOW IT WORKS
Why phentermine works differently
Phentermine works through the central nervous system rather than the GLP-1 pathway. In plain terms, it uses a different route to help reduce appetite — which is one reason it may be a strong fit for some patients.
1
Helps reduce appetite from the start
Phentermine helps reduce hunger by increasing norepinephrine signaling in the brain. Many patients notice that eating feels more manageable early on — especially compared with options that may take longer to build over time.
2
Built for daytime appetite control
Because phentermine is a stimulant-based medication, patients often describe feeling more alert and more in control of appetite during the day. It is typically taken in the morning so its effects align with waking hours.
3
Matched to the patient, not one protocol
Phentermine is prescribed based on your medical history, current medications, prior treatment response, and tolerability. The goal is to find a dose and plan that is effective, appropriate, and sustainable under provider supervision.
Different pathway. Same goal.
Helping patients feel less hungry, eat more comfortably, and make progress with provider guidance.
Side Effects
What patients report
Phentermine is a stimulant, so side effects differ from GLP-1 medications. Most are mild, manageable, and improve as the body adjusts.
|
Dry mouth |
COMMON |
|
Difficulty sleeping |
COMMON |
|
Increased heart rate |
COMMON |
|
Restlessness |
LESS COMMON |
|
Constipation |
LESS COMMON |
|
Headache |
LESS COMMON |
|
Elevated blood pressure |
LESS COMMON |
Taking phentermine at 6 a.m. minimizes sleep disruption. Staying well-hydrated helps with dry mouth and constipation. Your provider monitors blood pressure at every visit and will adjust the dose or plan if needed.
Who should not take phentermine
Your provider evaluates cardiovascular health before prescribing. Phentermine is not appropriate for patients with uncontrolled high blood pressure, heart disease, hyperthyroidism, glaucoma, or a history of drug abuse. It is not prescribed during pregnancy or breastfeeding. Phentermine cannot be taken with MAO inhibitors or with stimulant ADHD medications such as Adderall or Ritalin.
If phentermine is not appropriate for you, your provider may recommend semaglutide or tirzepatide as an alternative.
Side Effects
What patients report
Phentermine is a stimulant, so side effects differ from GLP-1 medications. Most are mild, manageable, and improve as the body adjusts.
common
Most patients notice these early on. They typically ease within the first 1–2 weeks.
LESS common
Not everyone experiences these. Mention them at your follow-up if they occur.
Monitored at every visit
Who should not take phentermine
Phentermine is not appropriate for patients with uncontrolled high blood pressure, heart disease, untreated hyperthyroidism, or untreated glaucoma. It is not prescribed during pregnancy or breastfeeding. Phentermine cannot be taken with MAO inhibitors. We do not prescribe it if you are taking a stimulant ADHD medication such as Adderall or Ritalin.
If phentermine is not appropriate for you, your provider may recommend semaglutide or tirzepatide as an alternative.
Side effects vary by patient. This is not a complete list. Your provider reviews your individual history before prescribing and monitors your response at every follow-up.
Why Rivas Is Different
Obesity is a chronic disease. We treat it like one.
Phentermine works through the central nervous system rather than the GLP-1 pathway. In plain terms, it uses a different route to help reduce appetite — which is one reason it may be a strong fit for some patients.
“They didn’t fail. The system failed them.”
A 2019 study published in Obesity — the journal of The Obesity Society — analyzed nearly 14,000 adults (84% female) and found that patients who used phentermine for longer than 12 months lost significantly more weight at 6 months, one year, and two years compared to those who stopped at three months. Critically, longer-term use was not associated with any increased risk of cardiovascular events or death.
What most patients have already heard
How Rivas treats it
CLINICAL RESEARCH
Long-term phentermine produces greater weight loss
Lewis et al., Obesity, 2019 · ~14,000 adults, 84% female
Long-term use (>12 months)
Short-term use (≤3 months)
6 MONTHS
2x more
weight lost
1 year
2x more
weight lost
2 years
No increased
cardiovascular risk
Chart values are approximate representations of study findings. Individual results vary. Source: Lewis KH et al. Long-term safety and effectiveness of phentermine use. Obesity. 2019.
CLINICAL RESEARCH
The longer patients stayed on phentermine, the more weight they lost
Lewis et al., Obesity, 2019 · ~14,000 adults, 84% female · Long-term use group (>12 months)
Chart values are approximate representations of study findings. Individual results vary. Source: Lewis KH et al. Long-term safety and effectiveness of phentermine use. Obesity. 2019. Reflects patients without pre-existing cardiovascular disease treated under medical supervision.
A 2019 study published in Obesity — the journal of The Obesity Society — analyzed nearly 14,000 adults (84% female) and found that patients who used phentermine for longer than 12 months lost significantly more weight at 6 months, one year, and two years compared to those who stopped at three months. Critically, longer-term use was not associated with any increased risk of cardiovascular events or death.
Your Visit
What to expect at your first appointment
Most patients walk out with medication on the same visit. Here is what the appointment looks like.
1
Medical evaluation
Your provider reviews your health history, current medications, blood pressure, and weight. This determines whether phentermine is appropriate and what dose to start with
2
Leave with medication
Most patients receive their prescription at the same visit. Your provider covers dosing, timing, nutrition guidance, and what to expect in the first few days. Questions about side effects, sleep, hydration, and protein are all addressed before you leave.
3
Two-week follow-up
You return at two weeks to assess response, side effects, and progress. Individual results may vary.
Patient Guidance
How to get the most out of phentermine
Your provider will cover all of this at your first visit. Here is what to know before you start.
Take it before you begin your day
Phentermine absorbs best on an empty stomach, and taking it at the start of your waking hours means appetite suppression peaks when you need it most and fades before you sleep. Patients who take it later in their day consistently report more sleep disruption. Timing is one of the most controllable factors in your experience.
Expect energy. Use it.
Phentermine is a stimulant, and the energy is real. Patients often describe wanting to get up and move on day one. Channel it — even a daily walk materially improves outcomes. The energy window is an asset, not just a side effect to sit through.
Front-load your protein
The most common pattern: appetite suppression works all day, the patient barely eats, then the medication wears off in the evening and hunger returns hard. The fix is to eat your protein earlier — before you feel hungry — so you are not running a deficit by 8 p.m. Your provider will give you specific guidance at your first visit.
Choosing the Right Tool
Different tools. Flexible treatment strategy.
Phentermine and GLP-1 medications work through different pathways and can play different roles over the course of treatment. Some patients do well with one alone, while others may benefit from adding the second later if progress slows, appetite control changes, or a different approach is needed.
Oral Prescription
Phentermine
A fit for patients who prefer pills over injections, want an earlier effect, or may benefit from a different mechanism at certain points in treatment.
Weekly Injection
Semaglutide / Tirzepatide
A fit for patients who want a longer-building medication, need sustained appetite control, or may benefit from adding a second tool later in treatment.
Can phentermine and a GLP-1 be used together?
Yes, in some cases. Some patients begin with one medication and add the second later if they hit a plateau, need stronger appetite control, or would benefit from a different mechanism. This is decided individually based on medical history, blood pressure, tolerability, and treatment response.
Individualized Care
A treatment plan tailored to you
There is no one-size-fits-all approach to medical weight loss. Some patients do well with one medication alone, while others may benefit from adding a second later or starting with both from the beginning. Your provider adjusts the plan carefully based on your response, tolerability, and goals.
One medication may be enough
Many patients do well with one medication and continue making progress with regular follow-up.
A second medication may be added later
If progress slows, your provider may add a second medication to help restart momentum.
Some patients begin with both medications
For some patients, starting with both medications may be the right fit from the beginning.
Phentermine is FDA-approved and available at Maryland locations. GLP-1 medications are available at all locations, including telehealth. All treatment decisions are made by your provider.
Clinical Education
How your treatment plan may evolve over time
Phentermine and GLP-1 medications are not competing options. Depending on the patient, one may be enough, a second may be added later, or both may be appropriate from the start. A common approach is to begin with one medication and adjust over time if needed. Your provider determines this based on response, tolerability, and goals.
Treatment is individualized. Some patients stay on one medication alone, some add a second later in either direction, and some remain on both because the combination continues to feel effective and appropriate for them.
Frequently Asked Questions
Phentermine FAQ
Your initial visit is $195 and includes your first two weeks of phentermine. Follow-up visits start at $90 for a two-week supply or $115 for a monthly supply — medication included in both. If your provider recommends additional appetite suppressants or combination therapy, the cost may be adjusted. HSA and FSA cards are accepted. Pricing is subject to change.
Most patients notice appetite suppression the same day — within a few hours of the first dose. For patients new to phentermine, providers report seeing 7–10 pounds of loss in the first two weeks. For patients who have been on phentermine before, 3–5 pounds in the first two weeks is more typical. Individual results vary based on medical history, adherence, dose, and metabolism. Your provider will set realistic expectations at your first visit.
Obesity is a chronic disease, and phentermine can be part of long-term management under medical supervision — the same way blood pressure medication is used to manage hypertension over time. A 2019 study in Obesity — the journal of The Obesity Society — analyzed nearly 14,000 adults and found that patients who used phentermine longer than 12 months lost significantly more weight at six months, one year, and two years compared to those who stopped at three months. Longer-term use was not associated with increased cardiovascular risk. At Rivas, your provider evaluates progress and blood pressure at every visit and adjusts your plan accordingly.
No. Phentermine and GLP-1 medications like semaglutide work through completely different mechanisms. Phentermine is a stimulant that suppresses appetite through the central nervous system. Semaglutide is a GLP-1 receptor agonist that reduces hunger by acting on gut hormone pathways. Phentermine is an oral pill; semaglutide is a weekly injection. Both are used at Rivas for ongoing weight management under medical supervision and can be used together when clinically appropriate.
Yes. Combining phentermine with a GLP-1 medication is a common approach at Rivas, particularly for patients in a plateau or during the early titration period of a GLP-1 when full appetite suppression has not yet been established. Your provider monitors blood pressure and side effects closely when prescribing both medications together. This approach is evaluated individually — it is not appropriate for every patient.
No. Phentermine is a Schedule IV controlled substance. Federal and Maryland state regulations prohibit controlled substance prescriptions via telehealth without a prior in-person relationship, and we do not prescribe phentermine remotely under any circumstances. Phentermine is available at our Maryland clinic locations only. If you are interested in a weight loss medication that can be managed via telehealth, our providers can discuss semaglutide or tirzepatide — both of which are available through Rivas Telehealth.
No. Rivas does not prescribe phentermine to patients currently taking stimulant ADHD medications such as Adderall (amphetamine) or Ritalin (methylphenidate). Both phentermine and these medications are central nervous system stimulants, and combining them carries significant cardiovascular risk — including elevated heart rate, increased blood pressure, and potential cardiac events. If you currently take a stimulant ADHD medication, your provider can discuss alternative weight loss options at your visit.
We carry KVK Tech phentermine — an American-manufactured formulation widely regarded among providers for consistency and quality. The classic tablet is white with blue speckles and is taken once daily in the morning. Your provider will confirm the right formulation and dose for you at your visit.
Phentermine 37.5 refers to a common tablet strength of phentermine hydrochloride, typically taken once daily in the morning. Phentermine is also available in other strengths and in capsule form. Your provider determines the right formulation and dose based on your individual history, current medications, and prior experience with phentermine — there is no one-size-fits-all protocol.
Related Reading
Learn more
More on phentermine, weight loss medication, and what to expect — from the Rivas GLP-1 Latest News blog.
Clincal Guide
How Phentermine Works In The Body
A clinical guide to phentermine: how it works, dosing, side effects, who qualifies, and how to get the best results. From the Rivas Medical clinical team.
Read the guide →
The Jumpstart You’ve Been Looking For
Phentermine available at Maryland locations only