How long can you take phentermine for weight loss?
Daniel Martin
Updated on March 27, 2026
How long can you take phentermine for weight loss?
Many doctors prescribe phentermine, on its own, to patients for more than 12 weeks. And anecdotal reports from many of my colleagues suggested that it was helpful for many patients long-term. But there’s a lack of research on its longer-term safety and efficacy.
How quickly does Phentermine work?
Phentermine is absorbed through the gastrointestinal tract and reaches peak concentrations in the blood in three to 4.4 hours, by which time you should start feeling the effects, alerting you that the drug is working. The short-term effects of Adipex may include: Decreased appetite.
Is Phentermine A good weight loss pill?
Phentermine alone, however, has been used for decades and appears to be a safe and effective weight loss medication when used in the short-term in healthy individuals. One study found that phentermine significantly reduced weight without raising blood pressure or causing other heart problems.
What should I eat while taking phentermine?
Great sources of fiber are beans, whole grains and brown rice, nuts, baked potatoes (but you have to eat the skin), berries, bran cereal and vegetables. Fruits and Vegetables: The water and fiber in fruits and vegetables will add volume to your dishes, so you can eat the same amount of food with fewer calories.
What happens when I stop taking phentermine?
If you stop taking the drug or don’t take it at all: You may not lose weight. If you take this drug for a long period of time and stop it suddenly, you may have extreme fatigue and depression. If you miss doses or don’t take the drug on schedule: Your medication may not work as well or may stop working completely.
How much water should I drink with phentermine?
Water: The first rule of every diet is to drink lots of water. When taking phentermine you should be drinking at least 8 glasses of water per day in order to improve the functions of your body and assist in the release of water weight, as well as keeping you hydrated and less likely to misinterpret thirst for hunger.
Who should not take phentermine?
Do not use phentermine if you are pregnant or breast-feeding a baby. You should not use phentermine if you have glaucoma, overactive thyroid, severe heart problems, uncontrolled high blood pressure, advanced coronary artery disease, extreme agitation, or a history of drug abuse.
Is Topamax the same as phentermine?
Phentermine is in a class of medications called anorectics. It works by decreasing appetite. Topiramate is in a class of medications called anticonvulsants. It works by decreasing appetite and by causing feelings of fullness to last longer after eating.
How do you qualify for phentermine?
You should only take phentermine or weight loss if you are obese—with a body mass index (BMI) of over 30—or a BMI of over 27 if have another serious medical condition caused by obesity, like diabetes or hypertension.
Can I drink coffee on phentermine?
Both phentermine and caffeine are stimulants. They both can cause insomnia, increased heart rate and jitteriness. It is likely that if you use caffeine while taking phentermine these side effects will be increased. It is recommended that you limited you caffeine use while taking phentermine.