What is cold sensitivity?
Cold sensitivity while taking Mounjaro typically presents as feeling unusually cold, even in environments that previously felt comfortable.
This sensation may be particularly noticeable in the extremities, like our hands, feet, nose, and fingers, which may feel cold to the touch.
According to patient reports, some individuals experience a persistent feeling of being cold throughout the day, with extremities that feel significantly colder than their core body.
Many report normal body temperature readings despite feeling freezing, with some noting that healthcare providers commented on how cold their hands felt during examinations.
Why might Mounjaro cause cold sensitivity?
Research on why Mounjaro may cause cold sensitivity is very limited. However, there are several possible reasons that might help explain why Mounjaro can make us feel colder:
1. Mounjaro interacts with the brain region that controls temperature
Research suggests that Mounjaro may directly affect our body’s temperature control system.
Mounjaro works by mimicking GLP-1, a hormone that, alongside its role in lowering hunger, also affects how our body controls its internal temperature.
Mounjaro works by communicating with the hypothalamus, our appetite control centre. Interestingly, the hypothalamus also has a role in regulating our core body temperature.
Studies show that GLP-1 activates a pathway in the body, via the hypothalamus, that stimulates our brown fat tissue, a type of fat that generates heat to keep us warm.
A study on mice suggested that Mounjaro stimulated brown fat tissue in the same way it would respond to cold water exposure.
So, by mimicking GLP-1, Mounjaro may be ‘switching on’ pathways in the body that change how we would normally regulate our core temperature.
Still, the exact processes behind these effects are poorly understood, and studies in humans are limited.
2. Cardiovascular effects and reduced blood flow
Mounjaro can lower blood pressure, which is beneficial for heart health, but this means our body may send less blood to our hands and feet.
This reduced peripheral circulation helps explain why extremities, in particular, feel cold, as they’re receiving less warming blood flow, and our body prioritises core organs.
3. Reduced caloric intake and digestion
One reason Mounjaro may increase feelings of cold is due to reduced food intake, which affects body heat production.
When we digest food, it generates heat within our body through a process called diet-induced thermogenesis.
When Mounjaro suppresses our appetite and reduces caloric intake, this heat-generating effect may decrease, potentially leading us to feel colder than usual, particularly between meals.
4. Weight loss and reduced insulation
During weight loss, we lose some of our natural insulation. Body fat serves as thermal insulation, helping maintain body temperature.
As we lose this insulation, especially in the first few months, we might find ourselves more sensitive to temperature change, similar to how a thinner blanket provides less warmth than a thick one.
5. Energy expenditure
When we lose weight, our body changes how it manages energy, affecting how warm or cold we feel.
This is called ‘metabolic adaptation’. A process where our body will reduce the number of calories we’re burning each day to preserve fat during weight loss.
This energy-saving mode can make us feel noticeably colder, especially in our hands and feet.
Our body prioritises keeping vital organs warm by directing less blood flow to the extremities.
For people taking Mounjaro, this effect can be particularly noticeable because:
- You’re likely eating less food (which normally creates heat during digestion)
- You’re losing insulating fat more quickly than with diet alone
- Your body is adapting to these changes by preserving energy
Research suggests that people who’ve lost significant weight may have slightly lower body temperatures than others of similar size who haven’t recently lost weight. This isn’t dangerous, but it helps explain why feeling cold may occur during weight loss.
While uncomfortable, this cold sensitivity is a sign that your body is responding normally to weight loss.
How common is cold sensitivity?
The exact prevalence of cold sensitivity among Mounjaro users in the UK is difficult to determine.
This side effect does not appear among the most commonly listed side effects (affecting 5% or more of patients) in clinical documentation.
Official documentation predominantly features gastrointestinal symptoms like nausea, diarrhoea, and vomiting rather than temperature regulation issues.
However, patient reports suggest it may be more common than formal documentation indicates.
The consistency of reports across social media platforms and health information websites suggests this is a genuine side effect experienced by a significant subset of users.
“Chills” are listed under the “incidence not known” category of side effects by the Mayo Clinic, indicating this effect has been observed, but its frequency is not well established.
Clinical research directly addressing cold sensitivity with tirzepatide remains limited.
Managing cold sensitivity while taking Mounjaro
For patients experiencing cold sensitivity on Mounjaro, several management strategies emerge from UK user experiences and clinical understanding:
Environment
Using space heaters in commonly occupied spaces helps maintain comfortable ambient temperatures.
Employing electric blankets, especially at night, can counteract the most intense cold sensations that many report during sleep.
Setting thermostats 1-2 degrees higher than usual may make a significant difference in comfort.
Keeping a hot water bottle nearby during sedentary activities provides targeted warmth where needed.
Clothing
Wearing thermal or Sherpa socks keeps feet warmer, which can improve overall comfort.
Layering clothing, even indoors, provides adjustable insulation as your temperature needs change.
Using hats to prevent heat loss is especially important for those with less hair, as significant body heat escapes through the head.
Employing hand warmers in gloves during outdoor activities can prevent cold extremities in the winter months.
Keeping a warm jumper or blanket accessible at all times allows for quick adjustments when cold sensitivity flares.
Timing
The first few days after injection may bring more pronounced cold sensations as your body adjusts to the medication.
Fasting periods or times between meals typically intensify cold feelings due to reduced thermogenesis (the heat produced through digestion).
Evening hours bring increased cold sensitivity for many, possibly related to natural circadian rhythm temperature fluctuations.
Planning meal timing and injection schedule accordingly might help manage symptoms. For example, some patients find that having a small protein-rich snack can temporarily reduce cold feelings.
Nutrition
Ensure you eat three main meals a day, with snacks in between if needed.
Focus on protein-rich foods, which create more heat when digested than carbohydrates or fats (they have a higher thermogenic effect).
Stay well-hydrated, as dehydration can worsen cold sensitivity and make regulation more difficult.
Consider warm beverages like herbal teas throughout the day for comfort.
When to seek medical attention
While cold sensitivity is generally considered a benign side effect, consult your healthcare provider if you experience:
Extreme cold intolerance that significantly impacts quality of life or daily functioning.
Numbness or tingling in the extremities that persists or worsens over time.
Discolouration of fingers or toes (particularly blue or white) could indicate more serious circulatory issues.
Cold sensitivity accompanied by unusual fatigue or weakness that affects your daily activities.
Take home message
Despite not being prominently featured in medication guides, reports from Second Nature members and online forums suggest that cold sensitivity is a real and common experience among Mounjaro users.
This side effect appears to be driven by multiple factors, including Mounjaro’s impact on the brain, reduced peripheral blood flow, decreased thermogenesis from lower food intake, and reduced insulation from weight loss.
While typically not dangerous, cold sensitivity can impact quality of life and may require adaptation strategies.
As Mounjaro usage continues to grow for both diabetes management and weight loss in the UK, increased awareness of this side effect will help patients prepare appropriately.
For most patients, the benefits of improved blood sugar control and weight loss likely outweigh the inconvenience of feeling cold.
Simple adaptations like layering clothing, adjusting room temperature, and maintaining regular meals rich in protein can effectively manage this side effect while you continue to benefit from the medication.
Second Nature’s medication programmes
Second Nature provides Mounjaro as part of our Mounjaro weight-loss programme.
Why should you choose Second Nature over other medication providers if you’ve decided to try Mounjaro or Wegovy (assuming you’re eligible)?
For peace of mind.
Second Nature has worked with the NHS for over 6 years, providing weight-loss programmes across the UK.
While our Wegovy and Mounjaro weight-loss programmes are private and not currently used by the NHS, we’ve built the programmes focusing on scientific evidence, patient safety, and data security.
We hope that our 6+ years of working with the NHS and building a track record of effective weight-loss results will give you peace of mind to give us a try.
Please note: We generally recommend speaking with your GP/doctor before you start taking any new medication like Mounjaro. If you do sign up for Second Nature's Mounjaro programme, then we'll also send your GP a letter to let them know you've started a medication-supported weight-loss journey.
