Phentermine, Naltrexone and Other Weight Loss Medications: Options Beyond GLP-1s
GLP-1 medications like semaglutide and tirzepatide have changed weight loss treatment, but they aren’t the only options.
Other weight loss medications can help with specific problems like hunger, cravings, food noise, low energy, or trouble maintaining weight after weight loss. Some people use these medications instead of a GLP-1. Others use them with a GLP-1 or as part of a long-term maintenance plan.
The best choice depends on what you need help with. Someone who feels physically hungry all day may need a different approach than someone who isn’t hungry but still struggles with cravings or food noise.
Here are a few of the weight loss medications we may consider and when they can be helpful.
Phentermine for Weight Loss
Phentermine is a prescription stimulant that has been used for weight loss for decades. It helps reduce appetite and may also increase energy.
Phentermine may be a good option when:
- Hunger makes it hard to lose weight
- Appetite has increased after weight loss
- Weight loss has stalled
- Low energy contributes to overeating or less activity
- You need more support during weight maintenance
Phentermine is FDA-approved for short-term weight loss. It is also a controlled medication and requires a prescription.
Because phentermine is a stimulant, we screen patients carefully before prescribing it. We look at blood pressure, heart rate, heart history, anxiety, sleep, pregnancy risk, and other medications.
Possible side effects include a faster heart rate, higher blood pressure, anxiety, trouble sleeping, dry mouth, and constipation. Taking phentermine earlier in the day can help reduce sleep problems.
Low-Dose Naltrexone for Cravings and Food Noise
Naltrexone works differently from a typical appetite suppressant. It doesn’t necessarily make you less hungry. Instead, it works on the brain’s reward system and can make food feel a little less tempting or hard to resist.
For some people, that means fewer cravings and less “food noise.” You can still enjoy food, but it may be easier to have a few bites and move on instead of continuing to think about it.
Naltrexone can be especially helpful for people who say things like, “I’m not actually hungry, but I still want to snack,” or “Once I start eating something sweet, I have a hard time stopping.”
Low-dose naltrexone may be worth considering when:
- Food noise or cravings are making weight management harder
- You eat even when you aren’t physically hungry
- You have foods that seem to flip an ‘I want more’ switch
- You want a non-stimulant option
Low-dose naltrexone isn’t FDA-approved by itself for weight loss, but naltrexone is one of the ingredients in the FDA-approved weight loss medication Contrave.
One important catch: naltrexone blocks opioid medications. If you take an opioid for pain or expect to need one for an upcoming procedure, naltrexone may not be a good fit.
Combination Weight Loss Medications
Sometimes weight management isn’t about one thing. Hunger, cravings, food noise, and low energy can all show up together.
That’s where combination medications can be helpful. Instead of relying on one medication to do everything, we can target several of those challenges at once.
One interesting compounded option combines: Phentermine + naltrexone + caffeine + methylcobalamin (vitamin B12)
Each ingredient has a different role:
- Phentermine: helps turn down hunger and appetite
- Naltrexone: helps quiet cravings and the “I want more” feeling
- Caffeine: provides a little extra energy and alertness
- Methylcobalamin (B12): provides vitamin B12 to support normal energy metabolism and nervous system function
For the right person, this can be a useful option for weight loss or maintenance, especially when a GLP-1 isn’t the right fit or isn’t enough.
Because this is a compounded combination, we only prescribe it when the ingredients and doses make sense for you.
Can You Use Phentermine or Naltrexone With a GLP-1?
Yes. Often, you can.
A GLP-1 may be working well overall while one specific problem remains. For example, a patient may still have strong cravings despite better appetite control, or hunger may return as the GLP-1 dose decreases during maintenance.
Rather than automatically increasing the GLP-1 dose, we can look at what is actually happening and decide whether another medication makes sense.
Can Other Weight Loss Medications Help With GLP-1 Maintenance?
They may be useful for some patients.
Once you reach your goal weight, the focus changes from losing weight to keeping it off. Hunger and food noise can return as you lower your GLP-1 dose or space injections farther apart.
Some people choose to stay on a GLP-1 long term. Others gradually lower their dose. In certain patients, medications such as phentermine or naltrexone may become part of the maintenance plan.
There isn’t one maintenance strategy that works for everyone. The goal is to find the amount of support you need to maintain your results without using more medication than necessary.
What Is the Best Medication for Weight Loss?
Trick question! There isn’t one “best” weight loss medication. The better question is: what’s getting in your way right now?
Hunger, cravings, food noise, low energy, insulin resistance, poor sleep, hormone changes, and loss of muscle can all make weight loss or maintenance harder. And they don’t all need the same solution.
That’s why we use our full toolbox instead of automatically reaching for more medication or a higher dose. We also look for the root causes that may be making weight harder to manage in the first place, like hormone changes, poor sleep, insulin resistance, stress, or loss of muscle. Then we choose the science-backed options that make the most sense for you.
Sometimes that’s a GLP-1. Other times, phentermine or naltrexone makes more sense. For some patients, a combination works best. And sometimes the answer isn’t another medication at all.
The goal isn’t more medication. It’s the right tool for the right problem.
Weight Loss Medication Should Fit the Patient
At Flow Wellness, we use weight loss medications as tools, not as a one-size-fits-all plan.
We look at hunger, cravings, food noise, energy, body composition, metabolic health, nutrition, strength training, sleep, and your long-term goals. From there, we can decide whether a GLP-1, phentermine, naltrexone, combination treatment, or another approach makes the most sense.
The answer may be changing medication, lowering your dose as you move into maintenance, or taking a completely different approach. Sometimes the best next step has nothing to do with medication at all.
The goal isn’t just weight loss. It’s finding a plan that helps you reach your goal and actually stay there.
Ready for a Weight Loss Plan That Actually Fits You?
Whether you’re just getting started, stuck at a plateau, or trying to maintain the weight you’ve already lost, we’ll help you figure out what makes sense for your body and your goals.
Updated July 2026
Medically reviewed by Dr. Kevin Jones, MD
Board Certified in Obesity Medicine
Flow Wellness
GLP-1 Support in California, Oregon, and Washington
At Flow Wellness, we help patients understand every aspect of their GLP-1 treatment program, including medication dosing, side effect management, nutrition, and long-term success strategies.
Our medical weight loss program includes:
- Personalized provider guidance
- Multiple GLP-1 treatment options
- Nutrition and lifestyle coaching
- Body composition scans to track muscle and visceral fat
- Free initial consultation!
Whether you are located in Bend, Oregon, Seattle, Washington, or receiving care in California, Oregon, or Washington through telehealth, our team is available to help answer questions about your medication and treatment plan.
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