Otezla (apremilast) causes weight loss through a combination of gastrointestinal side effects and possible hormonal changes, though scientists are still debating exactly how much each factor contributes. In clinical trials, patients lost an average of about 2 kg (roughly 4.4 pounds) over the first year of treatment, with most of the loss happening in the first four months.
Two Competing Theories
The most straightforward explanation is that Otezla’s common side effects make people eat less. Nausea, diarrhea, decreased appetite, stomach discomfort, and vomiting are all reported side effects. When you feel nauseated or spend the day dealing with digestive issues, you naturally take in fewer calories. This “eat less because you feel lousy” mechanism is well documented and likely accounts for a significant portion of the weight change.
The second, more interesting theory involves a hormone called GLP-1, the same one targeted by drugs like Ozempic and Wegovy. Otezla works by blocking an enzyme called PDE4, which raises levels of a signaling molecule inside cells. Researchers hypothesized that this chain reaction also boosts GLP-1 activity, which slows digestion, reduces appetite, and improves blood sugar control. Several observational studies have reported that patients on Otezla see improvements in blood sugar markers alongside their weight loss, which would be consistent with a GLP-1 effect.
However, a controlled study published in Rheumatology directly measured GLP-1 levels in patients taking apremilast over six months and found no significant change. That result casts doubt on the GLP-1 theory, at least as a primary driver. The weight loss may be real without GLP-1 being the reason.
How Much Weight Loss to Expect
The FDA’s clinical review provides a clear timeline. Patients taking the standard dose lost an average of 1.5 kg (about 3.3 pounds) by week 16. The loss continued gradually: 1.8 kg by week 32, 2.0 kg by week 52, and 2.7 kg by week 78. After that point, the data suggest the trend may plateau or slightly reverse, with an average loss of 2.3 kg at week 91.
This is modest compared to dedicated weight loss medications. For most people, it amounts to a few pounds over several months. But for some patients, particularly those who are older or already underweight, even a small unintended drop can be clinically meaningful.
Why GI Side Effects Hit Hardest Early On
Otezla is started at a low dose and gradually increased over the first five days specifically to reduce nausea and diarrhea. Despite this ramp-up, many patients still experience digestive symptoms during the first few weeks. The FDA data showing the steepest weight loss in the first 16 weeks lines up neatly with this adjustment period. As the body adapts, the GI side effects often lessen, which would explain why the rate of weight loss slows considerably after those initial months even though it doesn’t fully reverse.
Patients over 65 and those with low blood pressure or low fluid volume are more likely to experience severe diarrhea, nausea, or vomiting, which raises the risk of more significant weight loss and dehydration in those groups.
Effects on Children and Adolescents
Weight loss is a particular concern in younger patients. The FDA prescribing information specifically warns that Otezla may decrease a child’s weight and height. Growth monitoring (both height and weight) is recommended for all pediatric patients on the medication, and treatment may need to be paused if a child is not growing or gaining weight as expected.
When Weight Loss Becomes a Problem
The FDA label instructs patients to have their weight monitored regularly throughout treatment. If weight loss is unexplained or clinically significant, the prescribing information recommends evaluating the cause and considering whether to stop the medication. There is no specific threshold in pounds or percentage listed. The judgment depends on the individual patient’s starting weight, overall health, and how the loss is affecting them.
If you’re tracking your weight on Otezla, a gradual loss of a few pounds over several months is consistent with what clinical trials showed and is generally expected. A rapid or large drop, especially if accompanied by persistent vomiting or diarrhea, warrants a conversation with your prescriber sooner rather than later.