Phentermine (Adipex-P, Lomaira) is a prescription weight-loss medication that suppresses appetite and has been widely used for decades. While the FDA limits its use to short-term treatment, typically up to 12 weeks, recent studies suggest that longer-term use may be both safe and effective for certain low-risk individuals.
One study found those using phentermine for over 12 months lost 7.4% more weight than those stopping after 3 months, with no increased risk of cardiovascular issues. Another study showed nearly 40% of initial non-responders achieved significant weight loss by 6 months, with no major cardiovascular risks observed.
Common side effects of phentermine include dry mouth, insomnia, constipation, dizziness, and increased heart rate, while rare but serious side effects can include high blood pressure or heart palpitations. Generic phentermine costs $10-$50 for a 30-day supply, while branded versions like Adipex-P are pricier.
It remains popular due to its affordability and history of use. However, it is not suitable for everyone. Individuals with a history of cardiovascular conditions, hyperthyroidism, glaucoma, or substance abuse should avoid phentermine.
If you cannot take phentermine or didn’t achieve the desired results, this article will explore alternatives to phentermine to help you find the right weight-loss solution.
6 Alternatives to Phentermine
Several phentermine alternatives are available, each with distinct characteristics:
Active ingredients: Naltrexone-Bupropion
Drug class: Anorexiants, combines an antidepressant (bupropion) and an opioid antagonist (naltrexone)
Dosage form and strength: Extended-release tablets (8 mg naltrexone/90 mg bupropion)
Dosage frequency: Up to 4 tablets per day
Common side effects: Nausea, constipation, headache, vomiting, dizziness, insomnia, dry mouth, and diarrhea.
Contraindications:
- During pregnancy or while pregnant
- Poorly managed high blood pressure
- History of seizures or conditions causing seizures
- Eating disorder
- Use of other medications with bupropion
- Ongoing opioid treatment
- Recent use of monoamine oxidase inhibitors (within 14 days)
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How does it work? Bupropion works by boosting certain brain chemicals that reduce hunger and increase energy use. However, it can also trigger a natural substance in the body that eventually slows this effect. Naltrexone, the other ingredient, blocks this slowdown, helping bupropion continue to support weight loss.
Is it effective? In a real-world study, patients using Contrave achieved significant weight loss, with an average reduction of 9.2% at 6 months and 9.7% at 12 months, far exceeding the results of the control group.
A systematic review of 14 studies also highlighted the potential of the naltrexone/bupropion combination in addressing behavioral and psychological factors tied to obesity, such as binge eating and emotional eating.
In one study, participants with moderate to severe binge eating symptoms saw improvements as early as week 4. By week 24, 83% reported little to no binge eating problems. These improvements were closely linked to better control over eating, reduced weight, and enhanced mood, with participants also experiencing relief from depressive symptoms.
Active ingredients: Orlistat
Drug class: Lipase inhibitors
Dosage form and strength: Capsules (120 mg)
Dosage frequency: Taken 3 times a day
Common side effects: Oily spotting, passing gas with oily or greasy residue, sudden need to go to the bathroom, fatty/oily stool, needing to go to the bathroom more often, and trouble controlling bowel movements.
Contraindications:
- Pregnancy
- Should not be used if the body cannot properly absorb nutrients
- Individuals with liver-related bile flow problems
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How does it work? Orlistat works by blocking enzymes that break down fats in the digestive system. By stopping these enzymes from working, orlistat prevents up to 30% of dietary fat from being absorbed, allowing it to pass out of the body undigested.
Is it effective? A 24-week study found that obese patients taking orlistat lost an average of 10.2 lbs. They also reduced their BMI by 0.4 points more than the placebo group and decreased their waist circumference by 1.9 inches.
In one of Xenical’s clinical trials, participants taking orlistat achieved an average weight reduction of 11% in the first year and maintained a 6.9% reduction over four years. They also had a lower incidence of type 2 diabetes compared to the placebo group.
In a separate study involving patients already diagnosed with type 2 diabetes, orlistat improved HbA1c levels, a key marker of blood sugar control, after one year of treatment. Additionally, these patients experienced greater weight loss, with a 3.89% reduction compared to 1.27% in the placebo group.
Active ingredients: Phentermine-Topiramate
Drug class: Anorexiants, combines a stimulant (phentermine) and an anticonvulsant (topiramate)
Dosage form and strength: Extended-release capsules (3.75 mg/23 mg, 7.5 mg/46 mg, 11.25 mg/69 mg, 15 mg/92 mg)
Dosage frequency: Once daily
Common side effects: Tingling or numbness, dizziness, altered taste, insomnia, constipation, dry mouth, depression, joint pain, fever, flu, and stretched or torn ligament.
Contraindications:
- Pregnancy due to possible birth defects, such as clefts in the baby’s mouth or face
- People with hyperthyroidism or glaucoma
- Individuals who have used monoamine oxidase inhibitors in the past 14 days
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How does it work? Qsymia works for weight loss by combining the effects of phentermine and topiramate. Phentermine acts as an appetite suppressant by stimulating the release of certain chemicals in the brain that reduce hunger. Meanwhile, topiramate promotes the feeling of fullness, reduces food cravings, and can alter the taste of certain foods, making them less appealing.
Is it effective? In one study, phentermine-topiramate resulted in a 4.1% weight reduction after 20 weeks, compared to 3.6% with phentermine alone.
A meta-analysis comparing phentermine-topiramate to other weight-loss medications found it to have the highest success rate, with 75% of participants achieving at least 5% weight loss. Over one year, phentermine-topiramate users lost 19.4 lbs.
Active ingredients: Semaglutide
Drug class: GLP-1 receptor agonist
Dosage form and strength: Prefilled, injectable pen (0.25 mg, 0.5 mg, 1 mg, 1.7 mg, 2.4 mg)
Dosage frequency: Once weekly
Common side effects: Nausea, diarrhea, vomiting, constipation, abdominal pain, headache, fatigue, indigestion, dizziness, abdominal distension, burping, low blood sugar in people with type 2 diabetes, flatulence, gastroenteritis, acid reflux, and nasopharyngitis.
Contraindications:
- History of pancreatitis
- Personal or familial history of medullary thyroid cancer or multiple endocrine neoplasia (MEN) 2A or 2B
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How does it work? Wegovy works by mimicking a natural hormone in the body called GLP-1 (glucagon-like peptide-1), which helps regulate appetite, digestion, and blood sugar levels. It affects specific areas of the brain that control hunger and fullness, reducing cravings and making you feel satisfied more quickly.
Additionally, Wegovy slows down how fast food moves from your stomach to your intestines. This prolonged digestion helps you feel full for a longer time after eating, decreasing the urge to snack or overeat.
Is it effective? Several studies have shown that Wegovy is highly effective in helping people lose weight. In a 68-week trial, those who took Wegovy lost an average of about 33 lbs, while those on the placebo lost only about 6 lbs.
In another trial focused on individuals with both type 2 diabetes and obesity, those who received Wegovy lost nearly 10% of their body weight, while those on the placebo lost only about 3%.
Interested in Wegovy? Here’s What You Should Know!
- Side Effects of Wegovy: Learn about potential side effects, including nausea and digestive changes, and how to manage them.
- Wegovy’s Dosing Schedule: Understand how Wegovy is taken, with its simple once-weekly injection schedule designed for convenience.
- How to Get Wegovy: Find out where to get it, including tips on affordability and savings options.
Active ingredients: Tirzepatide
Drug class: GIP and GLP-1 receptor agonist
Dosage form and strength: Prefilled, injectable pen and single-dose vial (2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg)
Dosage frequency: Once weekly
Common side effects: Nausea, diarrhea, vomiting, constipation, abdominal pain, indigestion, injection site reactions, fatigue, hypersensitivity reactions, burping, hair loss, and acid reflux.
Contraindications:
- Personal or familial history of medullary thyroid cancer or multiple endocrine neoplasia (MEN) type 2
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How does it work? Zepbound is similar to Wegovy. However, it mimics another hormone called GIP (glucose-dependent insulinotropic polypeptide). This dual action enhances its effectiveness for both weight loss and blood sugar control, possibly making it more suitable for individuals with severe obesity or diabetes.
Is it effective? In a 72-week clinical trial, participants taking the lowest dose of Zepbound (5 mg) lost an average of 33.9 lbs. Those on the highest dose of 15 mg achieved an average weight loss of approximately 48 lbs, representing nearly 21% of their baseline body weight.
Furthermore, the percentage of adults achieving at least 5% weight loss was:
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- 85.1% with Zepbound 5 mg
- 88.9% with Zepbound 10 mg
- 90.9% with Zepbound 15 mg
Exciting News!
Zepbound has recently gained approval for treating Obstructive Sleep Apnea (OSA). Learn how this dual-action medication can address both weight loss and OSA, its potential benefits, and what this means for patients seeking effective treatment.
6. Saxenda
Active ingredients: Liraglutide
Drug class: GLP-1 receptor agonist
Dosage form and strength: Prefilled, injectable pen (0.6 mg, 1.2 mg, 1.8 mg, 2.4 mg, 3 mg)
Dosage frequency: Once daily
Common side effects: Nausea, diarrhea, constipation, vomiting, injection site reactions, headache, hypoglycemia, indigestion, fatigue, dizziness, abdominal pain, higher-than-normal levels of the enzyme lipase in the blood, upper abdominal pain, fever, and gastroenteritis.
Contraindications:
- Pregnancy
- Personal or familial history of medullary thyroid cancer or multiple endocrine neoplasia (MEN) type 2
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How does it work? Liraglutide was the first GLP-1 receptor agonist approved for treating obesity in people without diabetes. Like Wegovy, it works by mimicking a natural gut hormone (GLP-1) that slows digestion, reduces glucagon release, and promotes insulin release, leading to weight loss.
Is it effective? A 20-week study with a 2-year extension found that Saxenda helped patients lose up to 12.8 lbs more than the placebo. Over two years, patients on higher doses maintained an average 17.2 lbs weight loss and reduced body fat by 15.4%.
Another 56-week trial showed Saxenda users lost an average of 17.6 lbs, compared to 5.7 lbs with placebo. It also improved heart health, blood sugar levels, and quality of life.
Switching to a Phentermine Alternative
Switching from phentermine to another weight loss medication should be done carefully, under the guidance of a healthcare professional, to ensure safety and effectiveness. Here’s what you should consider:
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- Consult your healthcare provider: Schedule an appointment with your doctor to discuss why you want to switch medications. They will evaluate your medical history, current health, weight loss progress, and potential side effects you’ve experienced with phentermine.
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- Understand why you’re switching: Common reasons include lack of effectiveness over time, side effects, and personal preferences or goals that may align better with another medication.
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- Transition plan: Your doctor may recommend a waiting period between stopping phentermine and starting a new medication to avoid adverse interactions. They will also advise on the best starting dose and monitor your response to the new medication.
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- Evaluate your lifestyle: Weight loss drugs are most effective when combined with healthy lifestyle changes, including a balanced diet, regular exercise, and behavioral interventions. Address habits that may impact your long-term weight management success.
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- Monitor for side effects and effectiveness: Regular follow-ups are essential to assess your progress, adjust dosages, and monitor for any side effects from the new medication.
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- Consider insurance and cost: Check your insurance coverage and medication costs. Many newer medications, such as Wegovy or Zepbound, may have savings programs to help reduce out-of-pocket expenses.
It’s important not to combine phentermine with other stimulants or medications without explicit guidance from your healthcare provider, as this could increase the risk of serious side effects, such as cardiovascular complications.
Summary
Contrave, Xenical, Qsymia, Wegovy, Zepbound, and Saxenda each take a unique approach to weight management, offering tailored benefits depending on individual needs. Collaborating with your healthcare provider is essential to determine the option that aligns best with your health goals and medical history.
Frequently Asked Questions
Related Articles
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