Phentermine is a medication prescribed to help patients with weight loss.

How much weight loss will I have with Phentermine?

There is a lot of variability in the older trials of Phentermine. Both the physician and the diet prescribed play a large role in the effectiveness of Phentermine for weight loss. The studies suggest that you need the best diet and exercise plan tailored to you, in order to lose the most weight with Phentermine. In the studies since 2000, patients who received phentermine lost twice as much weight (or more) than patients who followed the same diet & exercise plan but took a placebo (fake pill). In clinical experience, brands of phentermine which are absorbed better, work better.

Does Phentermine work?

Patients given dietary management and treated with “anorectic” drugs (like Phentermine) lose more weight on average than those given placebo plus diet. Phentermine does not work well unless a dietary and exercise plan is included with the medicine.

How does Phentermine work?

Phentermine suppresses appetite and increases your metabolic rate so you feel less hungry and burn more calories. It works by raising your noradrenaline levels which increases your sympathetic nervous system (“fight or flight”).

Does Phentermine stop working?

The appetite-suppressing effect may become less powerful over time. However, the metabolic boost frequently continues (the doubling of weight loss versus diet & exercise alone). Some patients become hungrier around 3-4 months because they stop following the diet as closely and they start eating foods that stimulate the appetite. Phentermine is still working, but eating the wrong foods can stimulate your appetite more than phentermine will suppress it. Frequently, the proper course of action is to increase adherence to the diet, rather than change the phentermine. However, if phentermine doesn’t work, stops working, or has an intolerable side-effect, you should ask your physician to switch to a different weight loss medicine. There are lots of options. Some patients have genetic obesity. Other patients have medical conditions which force them to take weight-gaining medications for their entire lives. For both groups, the benefits of lifelong phentermine might outweigh the risks.

Is Phentermine safe?

Hundreds of thousands of patients have taken Phentermine safely, without any side-effect. In 2005 acetaminophen (Tylenol) and ibuprofen (Advil/Motrin) caused 22% of drug-related ER visits, but phentermine caused only 0.09%. However, you should not take Phentermine if you have advanced arteriosclerosis, serious cardiovascular disease, moderate to severe uncontrolled hypertension, hyperthyroidism, hypersensitivity to sympathomimetic amines, or glaucoma. Phentermine should not be taken with MAO-inhibitors. Phentermine should not be taken if you have a history of drug abuse. The warning label states: “There have been rare cases of valvular heart disease in patients who reportedly have taken Phentermine alone. There have been rare cases of primary pulmonary hypertension in patients who reportedly have taken Phentermine alone”.

What side-effects might I experience?

Some patients experience no side-effects. Remember, the medicine makes your body have higher levels noradrenaline, which is a natural neurotransmitter which your body already makes. When your body has higher levels of this natural “fight or flight” neurotransmitter, you may have nervousness, restlessness, constipation, insomnia, dry mouth. The warning label lists side-effects of headache, elevated blood pressure, overstimulation, and palpitations. However, many patients who experience those symptoms have discovered that the culprit is mixing caffeine with phentermine, and they have no problems taking phentermine if they avoid coffee. If you feel you have side-effects, please write down any other medicines you may have taken recently. Often, it can be a different medicine/substance which caused the problem.