{"id":630562,"date":"2024-11-21T13:07:05","date_gmt":"2024-11-21T18:07:05","guid":{"rendered":"https:\/\/www.singlecare.com\/blog\/?p=630562"},"modified":"2025-04-08T13:48:33","modified_gmt":"2025-04-08T17:48:33","slug":"does-phentermine-cause-constipation","status":"publish","type":"post","link":"https:\/\/www.singlecare.com\/blog\/does-phentermine-cause-constipation\/","title":{"rendered":"Does phentermine cause constipation?"},"content":{"rendered":"

Just under <\/span>half of U.S. adults attempt to lose weight<\/span><\/a> in any given year, according to the CDC. Sometimes it\u2019s with diet and exercise. Other times, with prescription medicine. And among all the weight loss drugs on the market, <\/span>phentermine has been the most widely used<\/span><\/a> since its FDA approval in 1956. From a class of medications called anorectics, it can help suppress the appetite to assist weight loss. This drug may have helped millions of Americans shed unwanted pounds, but it also comes with the risk of common side effects, including constipation.\u00a0<\/span><\/p>\n

It doesn\u2019t happen to everyone, but it\u2019s possible if you take <\/span>phentermine for weight loss<\/span><\/a>. How does it cause constipation? How can you manage it? When should you see a healthcare provider? Read on for all the health information you need.\u00a0<\/span><\/p>\n

Does phentermine cause constipation?<\/span><\/h2>\n

Yes, constipation is one of the most common side effects of <\/span>phentermine<\/span><\/a>. According to <\/span>a study from 2021<\/span><\/a>, 3.5% of patients who took 15 mg for six months reported it, along with 4.1% of patients who took 30 mg.\u00a0<\/span><\/p>\n

Phentermine is often combined with an anticonvulsant called topiramate. The duo works well together to reduce appetite, but may also cause constipation, along with other potential side effects. In <\/span>clinical trials<\/span><\/a> for a combination of phentermine and topiramate called Qsymia, 16% of patients taking 15 mg phentermine\/92 mg topiramate, 15% of patients taking 7.5 mg phentermine\/46 mg topiramate, and 8% of patients taking 3.75 mg phentermine\/23 mg topiramate reported constipation\u2014compared to 6% of patients in the placebo group.\u00a0<\/span><\/p>\n

However, some people experience the opposite, since diarrhea is also one of phentermine\u2019s potential adverse effects. It depends on the specific person and their body\u2019s reaction to the drug.\u00a0\u00a0<\/span><\/p>\n

Not all weight loss pills and appetite-suppressant drugs cause constipation, but because they often affect the digestive tract, many of these <\/span>medications can cause constipation<\/span><\/a> or other gastrointestinal side effects like nausea or stomach cramps. It\u2019s also one of the most prevalent adverse reactions for GLP-1 medications like Zepbound, Wegovy, and Saxenda, as well as other weight-loss medications like Contrave.\u00a0<\/span><\/p>\n

Relationship between phentermine and constipation<\/span><\/h2>\n

Phentermine can cause constipation because of the way it works within the body. According to <\/span>Dr. Pratima Dibba, MD<\/span><\/a>, board-certified gastroenterologist with Medical Offices of Manhattan and contributor to <\/span>https:\/\/www.labfinder.com<\/span><\/a>: \u201cPhentermine works on a certain part of the nervous system and increases a chemical messenger, also known as a neurotransmitter, called norepinephrine, which can impact the gastrointestinal tract, slowing motility and gastric secretion.\u201d<\/span><\/p>\n

Essentially, the drug activates the nervous system\u2019s \u201cfight or flight\u201d response, which diverts energy away from digestion in favor of what it presumes to be more urgent functions. As part of this process, it slows down peristalsis\u2014the series of muscle contractions that push food through the digestive tract. This slowed digestion helps with weight management, but it also might delay bowel movements.\u00a0<\/span><\/p>\n

\u201cIt can also cause dry mouth, which makes it easier for your body to lose water. It also speeds up your metabolism, which can make you sweat more, especially if you’re active,\u201d says <\/span>Dr. David Nazarian, MD<\/span><\/a>, founder of <\/span>My Concierge MD<\/span><\/a>. \u201cAnother thing is that phentermine can sometimes make it harder for your body to tell when you’re thirsty. This can make you less likely to drink enough water, especially when you’re sweating or losing fluids in other ways. When your body doesn’t have enough fluids, it can affect your digestive system and cause constipation.\u201d<\/span><\/p>\n

How long phentermine constipation lasts can depend on the person. However, the medication is generally only for short-term use. The Food and Drug Administration has only approved it for treatments of <\/span>up to 12 weeks<\/span><\/a> and typically <\/span>stays in your system for four days<\/span><\/a> after you stop taking it.\u00a0<\/span><\/p>\n

Management and treatment of phentermine-induced constipation<\/span><\/h2>\n

It\u2019s not ideal to get constipation from phentermine treatment, but the good news is that you\u2019ve got ways to deal with it. Here are a few of the most effective.\u00a0<\/span><\/b><\/p>\n