Mounjaro and Feeling Cold: Why It Happens and What You Can Do

Feeling unusually cold after starting Mounjaro (tirzepatide)? Here’s why it happens, what it means, and how you can manage it safely.

What Is Mounjaro and How Does It Affect the Body?

Mounjaro (tirzepatide) is a GLP-1 and GIP receptor agonist, designed to help regulate blood sugar, reduce appetite, and promote weight loss. It’s delivered through the KwikPen, a once weekly injection that’s popular for both diabetes and weight loss treatment in the UK.

By mimicking gut hormones, Mounjaro slows digestion and affects energy regulation, which can lead to both weight loss and some side effects, including feeling cold.

Why Does Mounjaro Make You Feel Cold?

While not listed as an official side effect by the manufacturer, many users report feeling persistently or unusually cold while on tirzepatide. Here’s why it happens:

1. Fat Loss Reduces Insulation

Losing weight, in particular rapid fat loss, results in reduced insulation and lower protection from environmental cold. Fat acts as a thermal buffer, and as your stores shrink, you may feel the cold more intensely, especially in your hands, feet, and face.

2. Lower Caloric Intake = Less Energy for Heat

On Mounjaro, many users consume significantly fewer calories. This results in a decrease in metabolic heat production, particularly during periods of fasting or calorie restriction.

3. Changes in Thyroid Function

Weight loss medications can subtly influence hormone levels. While rare, some users may experience changes in thyroid hormone activity, which plays a crucial role in regulating body temperature.

4. Reduced Muscle Mass

Muscles generate heat. If you’re losing weight rapidly without maintaining muscle mass, your body’s natural heat generation drops.

Is Feeling Cold Dangerous?

In most cases, feeling cold on Mounjaro is not dangerous, but it can be uncomfortable and impact your daily well being. However, in rare cases, it may indicate:

• Nutritional deficiencies (e.g., iron or B12)

• Undiagnosed hypothyroidism

• Low blood sugar levels, especially if you’re skipping meals

If you’re concerned, always speak to a healthcare provider. At Puri Pharmacy, we offer free consultations to help review symptoms and manage your Mounjaro plan.

How Common Is Feeling Cold?

Anecdotally, this ‘side effect’ is reported to be common among Mounjaro users, particularly in online forums and patient groups. It’s not always reported in trials, but users on 2.5mg and 5mg pens often describe feeling:

• Cold hands and feet

• General chilliness despite warm environments

• Night-time shivering or needing more blankets

• Sensitivity to wind or air conditioning

How to Manage Feeling Cold on Mounjaro

Eat Regular, Balanced Meals

Even if you’re not hungry, low calorie intake can worsen body heat loss. Try smaller meals every 3–4 hours with:

• Healthy fats (avocado, nuts)

• Lean protein (chicken, eggs)

• Complex carbohydrates (sweet potato, oats)

📩 Download our free GLP-1 friendly meal plan

Dress in Layers

Use thermal base layers or cotton undershirts to help retain warmth. Keep a blanket or hot water bottle handy when working from home.

Keep Hydrated

Dehydration can affect blood flow, making you feel even colder. Aim for 1.5–2L of water daily.

Monitor Iron and Thyroid Levels

Ask your GP or use a private blood testing service to check:

• TSH (thyroid-stimulating hormone)

• Iron and ferritin

• Vitamin B12

Need a test? Visit our Blood Testing Services

Gentle Exercise

Light movement (walking, yoga, stretching) can improve circulation and generate internal heat.

Adjust Your Dose or Escalation Speed

If coldness becomes unbearable, you may benefit from:

• Staying on your current dose longer

• Reducing frequency temporarily (under supervision)

Is It Different to Ozempic or Wegovy?

Yes. While Ozempic face and cold sensitivity are discussed with semaglutide, some patients report that Mounjaro’s dual hormone action (GLP-1 + GIP) causes slightly more intense thermoregulatory effects, especially early in treatment.

That said, everyone’s response is individual. What one person experiences on the 5mg KwikPen, another may feel only at 12.5mg or 15mg.

Could Feeling Cold Mean I’m Losing Too Much Weight?

If you’re consistently shivering, fatigued, or skipping meals due to low appetite, your body may be entering an energy-deficient state. This can slow metabolism, reduce thermogenesis, and even affect menstrual cycles in some women.

When to Seek Medical Advice

You should consult a pharmacist or GP if you:

• Feel cold even when dressed appropriately indoors

• Have dizziness, low blood pressure, or fatigue

• See signs of anaemia (pale skin, shortness of breath)

• Notice irregular or missed periods

We’re here to help you stay on track with your health goals safely.

Feeling cold on Mounjaro is a real and common experience for many people, especially during rapid weight loss. While it’s rarely a sign of danger, it can be uncomfortable and affect quality of life.

With the right strategy, nutrition, and dosing approach, you can continue benefiting from your Mounjaro KwikPen without sacrificing comfort.