Feeling cold is not listed among Ozempic’s official common side effects, but it’s a widely reported experience among people taking the medication. The FDA-approved label lists nausea, vomiting, diarrhea, abdominal pain, and constipation as the most common reactions (occurring in 5% or more of patients). However, “chills” does appear in the manufacturer documentation as a reaction with unknown incidence, and there are clear biological reasons why semaglutide can leave you feeling colder than usual.
Why Ozempic Can Make You Feel Cold
The most likely explanation comes down to eating less. Ozempic works partly by suppressing appetite, and most people on it consume significantly fewer calories than before. Your body generates heat as a byproduct of digesting food, a process called diet-induced thermogenesis. When you eat less, you produce less of that heat.
Research from Washington University in St. Louis found that long-term calorie restriction lowers core body temperature in a measurable way. People eating around 1,770 calories per day had an average 24-hour core temperature of 36.64°C, compared to 36.83°C in people eating a standard diet. That difference of roughly 0.2°C might sound small, but it’s enough to make you noticeably less comfortable in environments that never bothered you before. The effect was present around the clock but most pronounced at night, when core temperature in the calorie-restricted group dropped to 36.35°C versus 36.56°C in the control group.
This cooling effect appears to be an energy conservation response. When your body senses a sustained calorie deficit, it dials down metabolic output to stretch available fuel further. Levels of key hormones that regulate metabolism and body temperature, including thyroid hormone (T3), insulin, and leptin, all decrease during calorie restriction. Lower T3 in particular slows the cellular processes that generate body heat.
The Role of Fat Loss
Body fat acts as insulation. As you lose weight on Ozempic, you literally have less padding between your core and the outside air. This is especially noticeable for people who lose a significant amount of weight relatively quickly. The cold sensitivity tends to become more pronounced the more weight you’ve lost, and it can catch people off guard because their tolerance for cooler temperatures may have been quite different at a higher weight.
How GLP-1 Receptors Affect Body Heat
Ozempic is a GLP-1 receptor agonist, and GLP-1 receptors exist not just in the gut but also in the brain’s thermoregulation centers. Research published in the journal Adipocyte found that stimulating GLP-1 receptors in a specific region of the hypothalamus activates brown fat, the type of fat tissue that burns calories to generate heat. In animal studies, the GLP-1 drug liraglutide (a close relative of semaglutide) increased brown fat activity and the conversion of regular white fat into heat-producing “beige” fat.
This might sound like it should make you warmer, not colder. But the overall energy balance matters more. When the body is burning more calories through brown fat activation while simultaneously taking in far fewer calories from food, the net result can still be a lower resting temperature. The increased fat burning contributes to weight loss, but it doesn’t necessarily compensate for the reduced heat from lower food intake and shrinking insulation.
Low Blood Sugar as a Factor
Feeling cold can also signal low blood sugar, which is a known risk with Ozempic, particularly if you’re also taking insulin or other diabetes medications. Classic symptoms of low blood sugar include sweating, shakiness, dizziness, confusion, and a fast heartbeat. Cold sweats specifically are listed in the manufacturer documentation as a symptom with unknown incidence. If your cold sensation comes with any of these other symptoms, low blood sugar is worth checking.
Practical Ways to Stay Warmer
The cold sensitivity on Ozempic is manageable for most people. A few adjustments can make a real difference.
Eating enough is the most important one. While a calorie deficit is part of the weight loss process, extreme restriction makes cold intolerance worse. A moderate deficit of 500 to 750 calories below your maintenance level keeps weight loss on track without pushing your metabolism into deep conservation mode. Prioritizing protein helps here: protein has a higher thermic effect than carbs or fat, meaning your body generates more heat digesting it, and it also helps preserve muscle mass during weight loss.
Eating more frequently can also help. Smaller meals spread throughout the day keep a steadier stream of heat production going compared to one or two large meals. This approach has the added benefit of reducing nausea, one of Ozempic’s most common side effects.
Exercise raises core body temperature by several degrees during and after a session. Higher-intensity workouts produce more heat, but even a brisk walk will help. Regular exercise also builds and maintains muscle tissue, which is more metabolically active than fat and generates more baseline heat.
- Layer your clothing so you can adjust throughout the day as your temperature fluctuates
- Cover your extremities with socks and hats, since hands, feet, and your head lose heat fastest
- Keep warm drinks on hand like tea or broth, which warm you from the inside
- Bump up your thermostat by even one or two degrees, which can be enough to eliminate the chill
When Cold Sensitivity May Signal Something Else
Persistent cold intolerance that doesn’t improve with these strategies could point to a thyroid issue. Ozempic carries a boxed warning about thyroid tumors (based on animal studies), and an underactive thyroid independently causes cold sensitivity along with fatigue, weight gain, dry skin, and sluggishness. If you’re feeling cold alongside these other symptoms, thyroid function is worth investigating with a simple blood test. Anemia, which can develop if your diet becomes too restrictive, is another common cause of feeling cold that’s unrelated to Ozempic itself but can overlap with its use.