Introduction
Weight loss drugs have been around for a while now. Moreover, some have been making a comeback amid shortage issues and skyrocketing prices of newer options. Phentermine, which received FDA approval in 1959, has been resurfacing for its weight loss benefits, as well as its affordability. The drug helps you shed pounds by curbing your appetite and making you consume fewer calories.
Two major players currently in the weight loss scene are Ozempic and Wegovy, which share the same active ingredient, semaglutide.
With these options in the market, which is better? We compare semaglutide vs. phentermine and examine which one is more effective.
What is semaglutide?
Semaglutide is a drug called a glucagon-like peptide-1 receptor agonist, or GLP-1 Ra. Whenever we finish eating and blood sugar levels are high, a hormone, GLP-1, triggers insulin secretion to lower blood glucose. GLP-1 receptor agonists such as semaglutide act as GLP-1 doppelgangers, mimicking how GLP-1 triggers the release of insulin.
Another effect of taking semaglutide is slower digestion or gastric emptying. Because of this, people taking semaglutide feel fuller for longer. As a result, they don’t feel like eating as much, have fewer cravings, and end up shedding pounds.
There are three semaglutide brands currently out in the market: Ozempic, Wegovy, and Rybelsus. Both Ozempic and Rybelus has FDA approval to treat type 2 diabetes while Wegovy has FDA approval to treat obesity.
Despite drugmaker Novo Nordisk only marketing Wegovy to manage weight, many healthcare providers prescribe Ozempic or Rybelsus off-label for weight loss.
Eligibility
Every person is different and may respond differently to a medication. In the case of semaglutide, it’s not an over-the-counter drug that generally anyone can take. All semaglutide brands are only available via prescription as Ozempic, Wegovy, and Rybelsus all have specific diagnostic criteria.
For Ozempic and Rybelsus, for example, you need to have type 2 diabetes. Occasionally, doctors prescribe Ozempic for heart disease, as it has additional approval for lowering the risk of cardiovascular problems. Doctors may at times also prescribe them for those dealing with insulin resistance.
For Wegovy, you need a BMI of 27 or greater with one weight-related condition or BMI of 30 or greater.
Oral and subcutaneous semaglutide
Before buying semaglutide, it’s important to understand its different formats and the administration route you prefer. You may also want to take it daily or weekly.
There are two ways you can take semaglutide: either administering it orally or subcutaneously (injecting it under the skin).
Ozempic has two sister semaglutide brands: Wegovy and Rybelsus. Both Ozempic and Rybelsus have FDA approval to treat type 2 diabetes, while Rybelsus has FDA approval to treat obesity.
You can take Rybelsus orally or by mouth as it is in tablet form. For Ozempic and Wegovy, meanwhile, you administer these subcutaneously or under the skin as they come in injectable dosing pens.
Dosage and administration
Your doctor will typically start you off on a low dose, gradually increasing this until you reach a maintenance dose. This is to help your body adjust to semaglutide.
You can inject both Ozempic and Wegovy in three different areas: your 1) abdomen, 2) thigh, or 3) upper arm. For Rybelsus, meanwhile, you take it orally once daily on an empty stomach.
Make sure that you are not injecting into a muscle or vein. It is best to use a different injection site with every injection. However, if you want to use the same injection site, pick a different spot in that area.
Common and serious side effects
Whether you use Ozempic or Wegovy for weight management, you will still potentially face developing side effects.
Gastrointestinal reactions account for 10% or more of semaglutide’s side effects. These include:
- nausea (up to 44% of cases),
- diarrhea (up to 30%),
- vomiting (up to 24%),
- constipation (up to 24%),
- abdominal pain (up to 20%),
Other common side effects of semaglutide occuring in 1 to 10% of cases include indigestion, belching, gassiness, gastroenteritis, or gastritis. Gastroenteritis is the short-term infection and inflammation of the digestive system, while gastritis is inflammation of the stomach lining.
Note that these side effects of semaglutide are mild and you can manage thesewith the help of your healthcare provider. Semaglutide’s more serious adverse effects, meanwhile, are rare.
Serious side effects
The more serious side effects of semaglutide include allergic reactions, hypoglycemia, pancreatitis, kidney problems, and thyroid c-cell tumors.
Efficacy of semaglutide
Several studies have proven semaglutide’s efficacy in regulating blood sugar levels and promoting weight loss. Apart from these benefits, the drug may also play a positive role in improving cardiovascular health.
What is phentermine?
Phentermine, which received FDA approval in 1959, is a stimulant drug that helps you lose weight by suppressing your appetite. It triggers a surge of norepinephrine—a neurotransmitter and hormone—in the parts of the brain that control appetite. It’s available as a generic drug, also under the brand names Adipex-P, Obenix, and Lonamin.
No data indicates phentermine can burn fat directly. But if you take it along with a lower-calorie diet and an ample amount of physical activity, you should experience fat loss.
Although phentermine’s chemical structure may be similar to amphetamines it does not possess the same addictive qualities. Amphetamines are stimulant drugs that speed up the central nervous system and boost feel-good chemicals in the brain. However, you can still misuse it and build dependency.
Eligibility for phentermine
Patients eligible for phentermine must have a BMI of at least 30 mg/kg². Alternatively, they must have a BMI of 27 mg/kg² if they have other conditions like high blood pressure/cholesterol. You must be at least 17 years old and above to take phentermine.
Doctors do not recommend phentermine for those who have glaucoma, hyperthyroidism, or a history of heart disease.
Dosage and administration of phentermine
You must take phentermine orally. It is available in 15 mg, 30 mg, and 37.5 mg strength capsules, tablets, or disintegrating tablets. Take it mid-morning or in two doses.
You should only use it for the short term, typically about 12 weeks or three months. You should expect to lose at least five percent of your starting body weight during this period.
After taking phentermine, you should feel your appetite weaken. A 30 mg tablet, for example, can suppress your appetite for 12 to 14 hours.
Safety and efficacy of phentermine
If you’re considering taking phentermine, it’s important that you know about its potential risks and side effects. As a stimulant, most of its side effects include:
- Nervousness and excitability
- Insomnia
- Headache
- Dry mouth or thirst
- Sweating
- Fast heart rate
- Nausea
- Constipation
Pulmonary hypertension
Although phentermine doesn’t have any boxed warnings, it has serious rare side effects like high blood pressure in the lungs. It is otherwise known as pulmonary hypertension or PPH, and leaking heart valves (valve regurgitation).
These side effects were first observed when phentermine was combined with fenfluramine (the combination was known as fen-phen) or dexfenfluramine.
In 1997, the FDA discontinued fenfluramine and dexfenfluramine due to these safety issues. Fenfluramine treats seizures linked to Dravet syndrome (genetic epilepsy starting in infancy) and Lennox-Gastaut syndrome (severe form of epilepsy).
In 2020, the FDA re-approved fenfluramine for a certain type of seizure disorder. They established a safety program to ensure that the drug is only prescribed for approved conditions.
High blood pressure
Phentermine has also been found to trigger extremely high blood pressure if taken in tandem with monoamine oxidase inhibitors (MAOIs). Some examples of MAOIs include those used for Parkinson’s disease and depression.
MAOIs inhibit the chemical monoamine oxidase (MAO) to help enhance mood. They also increase levels of a hormone that slows down the development of Parkinson’s disease.
Efficacy of phentermine
Studies also showed that weight loss on phentermine depended on the dosage and the duration of the treatment. Although the FDA-approved period is 12 weeks, research reveals that it is more beneficial to prolong the use of phentermine. Data showed that after six months, those on 15mg of phentermine daily could lose 7% of their starting body weight.
Which is better, semaglutide or phentermine?
There have not been any studies directly comparing semaglutide and phentermine. However, a 2021 study discovered that people on semaglutide lost more body weight than those weight loss drugs like phentermine.
Cost-wise, phentermine is priced significantly cheaper than semaglutide as it’s available in generic form. You can get phentermine for as low as $100* out-of-pocket for phentermine. Meanwhile, semaglutide costs around $830 to $1,349.02* if it is not covered by insurance.
If we look at the uses of the two, semaglutide appears to be more advantageous. While phentermine is for weight management, semaglutide is for weight management, blood sugar regulation, and minimizing risk of heart problems. Some examples are heart attack, stroke, and death in adults with type 2 diabetes and heart disease.
The good news about phentermine is that it is usually covered by insurance, especially if you have type 2 diabetes.
Both semaglutide and phentermine have features that are better than the other. It depends on your personal criteria on how to evaluate the two drugs.
Taking semaglutide and phentermine simultaneously
Technically, it’s possible, if advised by your healthcare provider, but it’s not recommended. If you take them together, you will typically start on one of the drugs and gradually increase the dosage.
However, If the maximum dose is not delivering results, you may be asked to take a second drug. Note that the more medications you take, the greater your risk of experiencing more pronounced side effects.
As the effect of combining semaglutide and phentermine has not been studied, it is not advisable to take them simultaneously.
Conclusion
Phentermine has been around since the 1950s and is making a comeback amid pricier weight management drugs such as semaglutide. It has been proven to be effective in curbing appetite and promoting weight loss.
As phentermine is a mild stimulant, most of its side effects involve the central nervous system. Although its chemical structure is similar to that of the stimulant amphetamine, it does not possess the same addictive qualities.
Both phentermine and semaglutide are effective in suppressing appetite and reducing weight. But studies show that you can lose more weight on semaglutide than on other drugs such as phentermine.
Cost-wise, phentermine is priced significantly cheaper than semaglutide. It can also be covered by your health insurance especially if you have type 2 diabetes. This presents a great alternative to those searching for a non-semaglutide option amid its shortage issues.
Glossary of terms:
- GLP-1: Glucagon-like peptide-1 is a gut-based hormone involved in the secretion of insulin to lower blood sugar levels typically elevated after meals.
- GLP-1 Ra: Glucagon-like peptide-1 receptor agonist. It mimics the actions of GLP-1.
- MAOIs: Monoamine oxidase inhibitors. These inhibit the chemical monoamine oxidase (MAO) to help enhance mood and increase levels of a hormone that slows down the development of Parkinson’s disease.
