Qsymia vs. Zepbound for weight loss: side-by-side comparison

Weight loss medication can be a powerful tool for helping people lose weight and keep it off. Several prescription options are available, each with its own pros, cons, and price tags. Let’s compare two options — Qsymia vs. Zepbound — to see how they stack up. 

Qsymia (phentermine/topiramate) and Zepbound (tirzepatide) differ in several ways. One of the biggest differences: Qsymia is a daily pill, while Zepbound is a weekly injection.

Another key difference is their indications — aka the specific uses that have been approved by the US Food and Drug Administration (FDA).

Qsymia is FDA-approved for long-term weight management in the following people, in combination with diet and exercise:

• Adults and adolescents (age 12+) with obesity

• Adults with overweight and at least one weight-related medical condition 

Zepbound is FDA-approved, along with diet and exercise, for:

• Long-term weight management in adults with obesity or overweight and at least one weight-related condition 

• Obstructive sleep apnea in adults with obesity

An overview of how these two medications compare:

Qsymia and Zepbound work differently in the body to help with weight loss. 

Qsymia 

Qsymia is a once-daily oral capsule. It contains two active ingredients that work together to support weight loss: 

• Phentermine is a mild stimulant. It suppresses appetite by stimulating the release of certain brain chemicals and may increase how much energy (i.e. calories) you burn. 

• Topiramate is an anti-seizure medication. It’s thought to enhance appetite suppression and reduce binge eating. But exactly how topiramate works for weight loss isn’t entirely clear. 

Zepbound

Zepbound is a once-weekly subcutaneous (under-the-skin) injection. Its active ingredient is tirzepatide, which works by mimicking two natural gut hormones:

• GLP-1 (glucagon-like peptide 1): GLP-1 helps lower blood sugar, slow stomach emptying, and reduce the release of glucagon (a hormone that raises blood sugar).

• GIP (glucose-dependent insulinotropic polypeptide): GIP helps regulate metabolism by sending signals to the brain and fat tissue. 

A major difference between Qsymia vs. Zepbound is that Qsymia is a weight loss pill and Zepbound is an injection. Zepbound doesn’t come in oral pill form.

Qsymia

Qsymia is an oral extended-release capsule that you take once daily. The best time of day to take Qsymia is the morning; taking it late in the day may cause trouble sleeping.

How to take it: Take Qsymia by mouth, with or without food. 

Doses: Qsymia comes in four strengths (phentermine mg/topiramate mg), including 3.75 mg/23 mg, 7.5 mg/46 mg, 11.25 mg/69 mg, and 15 mg/92 mg.

Starting dose: 3.75 mg/23 mg

Maintenance doses: 7.5 mg/46 mg, 11.25 mg/69 mg, or 15 mg/92 mg

Maximum dose: 15 mg/92 mg

Dosing: After two weeks on the starting dose of 3.75 mg/23 mg, your provider typically increases it to 7.5 mg/46 mg. After 12 weeks of treatment, your provider may increase your dosage to 11.25/69 mg once daily. Two weeks later, they may increase it to 15 mg/92 mg. 

Your Qsymia dose may vary based on how your body responds, and people with kidney or liver problems may need a lower maximum dose.

Zepbound 

Zepbound is a once-weekly injectable medication that’s available as a single-use, prefilled injector pen and a single-use vial. 

How to take it: Inject Zepbound under the skin of the abdomen, thigh, or upper arm on the same day each week.

Doses: Zepbound comes in six strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg. 

Starting dose: 2.5 mg

Maintenance doses: 5 mg, 10 mg, or 15 mg

Maximum dose: 15 mg

Dosing: After four weeks at the starting dose of 2.5 mg, your provider typically increases it to 5 mg and may raise it by 2.5 mg every four weeks until you reach the maintenance Zepbound dosage that works for you. 

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Zepbound usually leads to more weight loss than Qsymia, but weight loss isn’t the only deciding factor. Preferences for injections vs. pills, costs, and side effects all play a role. A healthcare provider can help you decide which option, if any, makes the most sense.

How much weight can you lose on Qsymia vs. Zepbound?

People typically lose 5%–11% of their body weight on Qsymia, compared with 15%–21% on Zepbound, based on average results from separate studies. 

There are no head-to-head trials comparing Zepbound vs. Qsymia, but the results below show how each medication performed against placebo:

Qsymia: Trials show that Qsymia is better than placebo for weight loss. After about a year of treatment, participants experienced meaningful weight loss, with average results varying by dose:

• 3.75 mg/23 mg: 5% weight loss

• 7.5 mg/46 mg: 8% weight loss

• 15 mg/92 mg: 10% or 11%

Zepbound: A clinical trial found that Zepbound led to greater weight loss than placebo, with about half of Zepbound users losing 20% or more. After 72 weeks, average weight loss results were dose-dependent:

• 5 mg: 15% weight loss

• 10 mg: 20% weight loss

• 15 mg: 21% weight loss

TL;DR: Zepbound is likely a better choice in terms of how much weight you can expect to lose. Both drugs can be effective, especially at higher doses.

How long does it take to see results on Qsymia vs. Zepbound?

Weight loss usually begins within the first few months with either medication. Here’s what the estimated average weight loss timelines for people who finished the full studies look like:

*If you do not lose at least 5% of your body weight after 12 weeks on this dose, your healthcare provider may tell you to stop Qsymia.

Because these studies measured overall weight change rather than speed, individual results may differ. So, comparing your progress to these timelines isn’t the best way to determine effectiveness. Talk with your healthcare provider if results seem slower (or faster) than expected. 

Qsymia and Zepbound share some side effects, but their most common ones differ. The table below breaks down what was reported in studies.

✅ Common side effect (reported by at least 5% of trial participants)

*️⃣ Less common side effect

❌ Not reported in clinical trials

Qsymia side effects 

In adults, common side effects of Qsymia include:

• Tingling or numbness (paraesthesia)

• Dizziness

• Changes in how food tastes or a metallic taste in your mouth

• Trouble sleeping

• Constipation

• Dry mouth

Serious side effects are rare, but Qsymia may cause mood or sleep disorders, suicidal thoughts or behavior, problems with memory or attention, vision changes, and metabolic acidosis (too much acid in your blood). 

Other serious side effects may include slowed growth (in adolescents), severe skin reactions, increased body temperature, low potassium, and kidney problems. Qsymia also carries risks for abuse and dependence (Schedule IV controlled substance). 

Zepbound side effects 

Common side effects of Zepbound include: 

• Nausea

• Diarrhea

• Vomiting 

• Constipation

• Abdominal pain

• Indigestion

• Injection site reactions

• Fatigue

• Burping

• Hair loss

• Acid reflux

Serious side effects are rare but possible. Zepbound may increase the risk of pancreatitis, gallbladder problems, severe digestive effects that may cause dehydration or kidney injury, and suicidal thoughts or behaviors. People with diabetes also have a higher risk of eye problems and low blood sugar (if also taking certain diabetes drugs).

Zepbound has a boxed warning for a risk of thyroid tumors. Rodents developed thyroid cancer in studies of the drug. Because of the potential risk, Zepbound is not recommended for people with thyroid cancer or multiple endocrine neoplasia syndrome type 2.

You and your provider will review your medical history to check for any reasons that would make Qsymia or Zepbound unsafe for you.

Who shouldn’t take Qsymia?

You shouldn’t take Qsymia if you are pregnant, planning a pregnancy, breastfeeding, or if any of these conditions or factors apply to you:

• Glaucoma

• Overactive thyroid

• Allergic to phentermine, topiramate, yellow 5 dye, or other ingredients 

• Taking an MAOI (monoamine oxidase inhibitor) drug or took one in the past two weeks 

• Experiencing depression and suicidal thoughts

Who shouldn’t take Zepbound?

You shouldn’t take Zepbound if you have a history of:

• Medullary thyroid carcinoma (MTC), or if a family member has had it

• Multiple endocrine neoplasia syndrome type 2 (MEN2)

You also shouldn’t take Zepbound if you are:

• Pregnant or planning a pregnancy

• Allergic to tirzepatide or other ingredients in Zepbound

• Taking another tirzepatide product (Mounjaro) or GLP-1 medication

• Experiencing depression with suicidal thoughts

Qsymia usually comes with a lower price tag than Zepbound, but your actual cost can vary based on insurance, pharmacy, and savings programs. Both are brand-name medications with no generic versions available yet.

Qsymia

Without insurance, Qsymia costs as low as $98 per month with a manufacturer savings offer. The average retail price is nearly $300 per month.

Insurance coverage: Most commercial insurance plans cover Qsymia. But some insurance plans may not cover Qsymia or any other weight loss drugs.

Medicare Part D coverage: Medicare does not cover Qsymia or any other weight loss medications, as of current laws.

How to save on Qsymia: 

• Home delivery option: You can pay only $98 per month (regardless of the dose you take) by signing up for a savings offer for Qsymia that includes free shipping of the medication to your home. 

• Local pharmacy option: If you prefer your local pharmacy, you can check if you’re eligible for the Qsymia savings card. Commercially insured patients pay the first $70 of their copay with up to $65 covered after; cash-paying or uninsured patients can save $75 per month.

Zepbound 

The list price for Zepbound is $1,086.37 for a month supply. 

Insurance coverage: Insurance may not cover Zepbound. Some plans cover it, while others do not cover weight loss medications at all. 

Medicare Part D coverage: Medicare does not cover Zepbound for weight loss. Medicare excludes weight loss drugs entirely. There might be an exception if you’re taking Zepbound for sleep apnea. 

How to save on Zepbound:

• Lower-cost vials: Through cash-pay options from Ro and LillyDirect, single-dose Zepbound vials cost $299 per month (2.5 mg), $399 per month (5 mg), or $449 per month for higher doses (7.5 mg, 10 mg, 12.5 mg, or 15 mg) with a manufacturer offer.

• With insurance coverage: Commercially insured people with Zepbound coverage can pay as little as $25 for a one- or three-month supply through the manufacturer’s savings program, if eligible. 

• Without insurance coverage: Zepbound savings card offers a discounted price of $650 per month for people whose insurance does not cover Zepbound.

No, Qsymia and Zepbound are generally not taken together. There is very limited research on the safety or effectiveness of combining weight loss medications. 

Because of these unknowns, combining Qsymia and Zepbound should only happen under close guidance from a healthcare provider, if at all.

Yes, it’s possible to switch from Qsymia to Zepbound (or Zepbound to Qsymia). 

For example, you may want to try Qsymia first if you prefer a daily pill. But if you don’t lose at least 5% of your body weight after a few months on the highest dosage of Qsymia, your provider might recommend stopping it and switching to another option. They’ll also guide you on how to taper off of Qsymia.   

Qsymia and Zepbound aren’t the only options when it comes to weight loss treatments. Other FDA-approved medications, such as Wegovy (semaglutide), are available, and each has different pros and cons to consider. 

The following diabetes medications are sometimes used off-label for weight management as alternatives to Zepbound or Qsymia:

• Ozempic is a once-weekly semaglutide injection that is approved for people with type 2 diabetes but is commonly used off-label for weight loss.

• Rybelsus is an oral semaglutide tablet that’s taken once daily and may lead to moderate weight loss.

• Mounjaro is a weekly injection that contains tirzepatide, the same active ingredient found in Zepbound. 

• Victoza is a daily injection. It contains the same active ingredient as Saxenda (liraglutide) in a lower dosage and led to an average weight loss of 5% in a study of people with diabetes.

• Metformin is an inexpensive oral medication that can lead to small but sustained weight loss, averaging about 2% more than placebo over time. 

Get started

Qsymia and Zepbound are both FDA-approved weight loss medications, but they work differently and fit different needs. Here’s a quick recap:

• Zepbound is a weekly injection given under the skin, while Qsymia is a once-daily capsule. Both start at a low dose and increase over time until you reach the recommended dosage.

• Zepbound typically leads to more weight loss than Qsymia. Both are effective options, especially at higher doses, when combined with healthy lifestyle modifications.

• Cost and insurance coverage vary widely, and savings programs can significantly lower out-of-pocket prices.