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Weight lossTwo labels compared

Phentermine vs Qsymia

Qsymia contains phentermine together with extended-release topiramate. Phentermine on its own is a separate, older approval. The most important difference between the two labels is not the extra ingredient but the length of use each one approves.

Qsymia

Ingredient
Phentermine and topiramate extended-release
Approved for
Long-term weight managementcovers weight loss
Supply
Prescription
Boxed warning
None
Pharmacy cost
$3.31 per tablet, capsule or pen, genericwhat pharmacies pay to buy it, not the price at the counter
Vivus LLC. Label version 42, effective 22 April 2026.

Phentermine hydrochloride

Ingredient
Phentermine hydrochloride
Approved for
Weight reduction, short term onlycovers weight loss
Supply
Prescription
Boxed warning
None
Pharmacy cost
$0.085 per tablet, capsule or pen, genericwhat pharmacies pay to buy it, not the price at the counter
Sun Pharmaceutical Industries, Inc.. Label version 10, effective 14 July 2025.
01From the FDA label

Side by side, straight from the labels

Generated from the two source labels, not typed out by hand, so it cannot drift from what the regulator approved. Rows where both labels say exactly the same thing are marked.

Active ingredientQsymiaPhentermine and topiramate extended-releaseCombination anorectic and antiepilepticPhentermine hydrochloridePhentermine hydrochlorideSympathomimetic amine anorectic
Approved forQsymiaLong-term weight managementPhentermine hydrochlorideWeight reduction, short term only
Supplysame in bothQsymiaPrescriptionPhentermine hydrochloridePrescription
What pharmacies payAcquisition cost, not retailQsymia$3.31 per tablet, capsule or pen, genericPhentermine hydrochloride$0.085 per tablet, capsule or pen, generic
Boxed warningsame in bothQsymiaNonePhentermine hydrochlorideNone
What the FDA approved it forQsymia
  • QSYMIA is indicated in combination with a reduced-calorie diet and increased physical activity to reduce excess body weight and maintain weight reduction long term in: Adults and pediatric patients aged 12 years and older with obesity Adults with overweight in the presence of at least one weight-related comorbid condition QSYMIA is a combination of phentermine, a sympathomimetic amine anorectic,...
  • Adults with overweight in the presence of at least one weight-related comorbid condition.
  • Limitations of Use: The effect of QSYMIA on cardiovascular morbidity and mortality has not been established.
  • The safety and effectiveness of QSYMIA in combination with other products intended for weight loss, including prescription and over-the-counter drugs, and herbal preparations, have not been established.
Phentermine hydrochloride
  • Phentermine hydrochloride is indicated as a short-term (a few weeks) adjunct in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity for patients with an initial body mass index ≥ 30 kg/m 2, or ≥ 27 kg/m 2 in the presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia).
  • Below is a chart of body mass index (BMI) based on various heights and weights.
  • BMI is calculated by taking the patient's weight, in kilograms (kg), divided by the patient's height, in meters (m), squared.
  • Metric conversions are as follows: pounds ÷ 2.2 = kg; inches × 0.0254 = meters.
  • The limited usefulness of agents of this class, including phentermine hydrochloride tablets, should be measured against possible risk factors inherent in their use such as those described below.
Forms and strengthsQsymia
  • QSYMIA extended-release capsules are available in four strengths (phentermine mg/topiramate mg): 3.75 mg/23 mg - purple cap imprinted with VIVUS and purple body imprinted with 3.75/23 7.5 mg/46 mg - purple cap imprinted with VIVUS and yellow body imprinted with 7.5/46 11.25 mg/69 mg - yellow cap imprinted with VIVUS and yellow body imprinted with 11.25/69 15 mg/92 mg - yellow cap imprinted with...
Phentermine hydrochloride
  • Tablets containing 37.5 mg phentermine hydrochloride (equivalent to 30 mg phentermine base).
  • Tablets containing 37.5 mg phentermine hydrochloride.
How the label says it is takenQsymia
  • Take orally once daily in morning.
  • Avoid administration in evening to prevent insomnia.
  • Recommended starting dosage is 3.75 mg/23 mg (phentermine mg/topiramate mg) daily for 14 days; then increase to 7.5 mg/46 mg daily.
  • Escalate dosage based on weight loss in adults or BMI reduction in pediatric patients.
  • See the Full Prescribing Information for details regarding discontinuation or dosage escalation.
  • Gradually discontinue 15 mg/92 mg dosage to prevent possible seizure.
Phentermine hydrochloride
  • Dosage should be individualized to obtain an adequate response with the lowest effective dose.
  • Late evening administration should be avoided (risk of insomnia).
  • Phentermine hydrochloride tablets can be taken with or without food.
  • Limit the dosage to 15 mg daily for patients with severe renal impairment (eGFR 15 to 29 mL/min/1.73 m 2)
Most common adverse reactionsQsymia
  • Most common adverse reactions in: Adults (incidence ≥ 5% and at least 1.5 times placebo) are: paraesthesia, dizziness, dysgeusia, insomnia, constipation, and dry mouth.
Phentermine hydrochloride
  • The following adverse reactions are described, or described in greater detail, in other sections: Primary pulmonary hypertension Valvular heart disease Effect on the ability to engage in potentially hazardous tasks Withdrawal effects following prolonged high dosage administration The following adverse reactions to phentermine have been identified: Cardiovascular Primary pulmonary hypertension...
Warnings and precautionsQsymia
  • Embryo-Fetal Toxicity: Can cause fetal harm.
  • In patients who can become pregnant, a negative pregnancy test is recommended before initiating QSYMIA and monthly during therapy; advise use of effective contraception.
  • QSYMIA is available through a limited program under a Risk Evaluation and Mitigation Strategy (REMS).
  • Suicidal Behavior and Ideation: Monitor for depression or suicidal thoughts.
  • Discontinue QSYMIA if symptoms develop.
  • Risk of Ophthalmologic Adverse Reactions: Acute myopia and secondary angle closure glaucoma have been reported.
  • Immediately discontinue QSYMIA if symptoms develop.
  • Consider QSYMIA discontinuation if visual field defects occur.
Phentermine hydrochloride
  • Coadministration with other drugs for weight loss is not recommended (safety and efficacy of combination not established).
  • Rare cases of primary pulmonary hypertension have been reported. Phentermine should be discontinued in case of new, unexplained symptoms of dyspnea, angina pectoris, syncope or lower extremity edema.
  • Rare cases of serious regurgitant cardiac valvular disease have been reported.
  • Tolerance to the anorectic effect usually develops within a few weeks. If this occurs, phentermine should be discontinued. The recommended dose should not be exceeded.
  • Phentermine may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle.
  • Risk of abuse and dependence. The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage.
  • Concomitant alcohol use may result in an adverse drug reaction.
  • Use caution in patients with even mild hypertension (risk of increase in blood pressure).
ContraindicationsQsymia
  • QSYMIA is contraindicated in patients: Who are pregnant With glaucoma With hyperthyroidism Taking or within 14 days of stopping a monoamine oxidase inhibitors With known hypersensitivity to phentermine, topiramate or any of the excipients in QSYMIA, or idiosyncrasy to the sympathomimetic amines.
  • Anaphylaxis and angioedema have occurred with topiramate Pregnancy
  • Hyperthyroidism
  • Taking or within 14 days of stopping monoamine oxidase inhibitors
  • Known hypersensitivity to any component of QSYMIA or idiosyncrasy to sympathomimetic amines
Phentermine hydrochloride
  • History of cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension)
  • During or within 14 days following the administration of monoamine oxidase inhibitors Hyperthyroidism Glaucoma Agitated states History of drug abuse Pregnancy Nursing Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines History of cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension)
  • Hyperthyroidism
  • Agitated states
  • History of drug abuse
  • Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines
Drug interactionsQsymia
  • Table 5 displays clinically significant drug interactions with QSYMIA.
  • Clinically Significant Drug Interactions with QSYMIA Monoamine Oxidase Inhibitors Clinical Impact Concomitant use of phentermine with monoamine oxidase inhibitors (MAOIs) increases the risk of hypertensive crisis.
  • Intervention Concomitant use of QSYMIA is contraindicated during MAOI treatment and within 14 days of stopping an MAOI.
  • Oral Contraceptives Clinical Impact Co-administration of multiple-dose QSYMIA 15 mg/92 mg once daily with a single dose of oral contraceptive containing 35 µg ethinyl estradiol (estrogen component) and 1 mg norethindrone (progestin component), in obese otherwise healthy volunteers, decreased the exposure of ethinyl estradiol by 16% and increased the exposure of norethindrone by 22%.
  • Although this interaction is not anticipated to increase the risk of pregnancy, irregular bleeding (spotting) may occur more frequently due to both the increased exposure to the progestin and lower exposure to the estrogen, which tends to stabilize the endometrium.
  • Intervention Inform patients not to discontinue their combination oral contraceptive if spotting occurs, but to notify their health care provider if the spotting is troubling to them.
Phentermine hydrochloride
  • Monoamine oxidase inhibitors: Risk of hypertensive crisis.
  • Alcohol: Consider potential interaction.
  • Insulin and oral hypoglycemics: Requirements may be altered.
  • Adrenergic neuron blocking drugs: Hypotensive effect may be decreased by phentermine.
Label versionQsymia22 April 2026Phentermine hydrochloride14 July 2025
02Written by us

One label approves a few weeks, the other approves long term use

The phentermine hydrochloride label indicates it as a short-term adjunct, and states that period plainly as a few weeks, in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction, for the management of exogenous obesity.

The Qsymia label indicates it in combination with a reduced-calorie diet and increased physical activity to reduce excess body weight and to maintain weight reduction long term, in adults and pediatric patients aged 12 years and older with obesity, and in adults with overweight who also have at least one weight-related condition.

This is the difference that matters most between the two documents, and it is stated in the indications rather than buried in the dosing section.

03Written by us

Qsymia states limitations that the phentermine label does not

The Qsymia label states that its effect on cardiovascular morbidity and mortality has not been established. It also states that safety and effectiveness in combination with other products intended for weight loss, including prescription and over-the-counter medicines and herbal preparations, have not been established.

Qsymia is an extended-release capsule available in four strengths, each pairing an amount of phentermine with an amount of topiramate. Phentermine on its own is a tablet at a single strength. The exact figures are in the table above, taken from each label.

04Written by us

The contraindications overlap, and the phentermine list is the longer one

Neither label carries a boxed warning. Both contraindicate pregnancy, glaucoma, hyperthyroidism, use during or within 14 days of a monoamine oxidase inhibitor, and known hypersensitivity or idiosyncrasy to the sympathomimetic amines. That overlap is what you would expect from a combination product built on phentermine.

The phentermine label then adds several that do not appear in the Qsymia list: a history of cardiovascular disease, given as coronary artery disease, stroke, arrhythmias, congestive heart failure and uncontrolled hypertension, along with agitated states, a history of drug abuse, and nursing. Its warnings section also states a risk of abuse and dependence, and directs that the least feasible amount be prescribed or dispensed at one time.

The Qsymia label separately notes that anaphylaxis and angiedema have occurred with topiramate.

05Written by us

What this page does not tell you

It does not say which one a person should take, and the difference in approved duration is not a ranking. Phentermine is a controlled substance in the United States, and both products are prescription medicines whose use is a decision for a prescriber.

06Written by us

Common questions

Is Qsymia just phentermine with something added?
Qsymia combines phentermine with extended-release topiramate in a single capsule, and holds its own FDA approval with its own label. It is not the phentermine label with an extra ingredient noted, and the two documents approve different lengths of use.
Why is phentermine on its own approved only for a few weeks?
The phentermine label states short-term use, a few weeks, in its indication. The reasoning behind that limit is not given in the label, and this page does not supply one.
Can phentermine and topiramate be taken separately instead?
That is prescribing outside the approved products and is a decision for a licensed clinician. Neither label describes taking the two ingredients as separate medicines.
07

Sources

Every fact above comes from one of these documents. The date is the effective date of the label version this page was built from.

Each stripe is one section of the label, each division in a stripe one entry in that section.

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Other comparisons in this category

Page last updated 23 August 2026

Compiled by the HealthyStudy editorial team from FDA source documents. No medical reviewer is credited on this page, because none reviewed it.