Tirzepatide for weight loss

*SURPASS-5 Clinical Trial

Tirzepatide is the active ingredient in the injectable weight loss treatment Mounjaro. It belongs to a family of medications called glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonists.

GIP and GLP-1 are hormones that occur naturally in your body. Tirzepatide works by imitating these 2 hormones by attaching to the same receptors. This causes a reduced appetite as it sends signals to your brain that you’ve eaten, and slows down your digestive system so that you remain fuller for longer. It can also lower your blood sugar levels.

You may hear tirzepatide being referred to as a ‘dual receptor agonist’ because it mimics 2 hormones. It received a lot of attention because it’s the first GLP-1 injection to mimic a second hormone. Other GLP-1 weight loss injections include liraglutide (Nevolat) and semaglutide (Wegovy and Ozempic).

In weight loss studies, called SURMOUNT-1 and SURMOUNT-2, patients who received tirzepatide treatment showed significant weight loss compared to those treated with placebo. In the SURMOUNT-1 study involving 2,539 obese or overweight patients with one weight-related health condition, more than 96% of people who received 15mg of tirzepatide lost at least 5% of their body weight after 72 weeks of treatment.

How much weight can you lose on tirzepatide?

In studies for people with obesity or who were overweight with a weight-related medical condition, those taking the highest dose of 15mg once weekly lost 22.5% of their body weight after 72 weeks. Those taking the 10mg maintenance dose of tirzepatide once weekly lost on average 21.4%.

In a study on weight loss and type 2 diabetes, people lost on average 13.4% on 10mg and 15.7% on 15mg over 72 weeks.

Tirzepatide follows a dosage schedule for weight loss, designed to help your body get used to the medication with minimal side effects and to help you find the best dose.

The tirzepatide dosage schedule for weight loss is as follows:

1. Starting dose (weeks 1 to 4) – 2.5mg per week.
2. Weeks 5 to 8 – 5mg per week. This is also a maintenance dose. People who stay on this dose lose an average 16% of their starting weight in 72 weeks.
3. Weeks 9 to 12 – 7.5mg per week.
4. Weeks 13 to 16 – 10mg per week. This is also a maintenance dose. People who stay on this dose lose an average 21.4% of their starting weight in 72 weeks.
5. Weeks 17 to 20 – 12.5mg per week.
6. Weeks 21+ – 15mg per week. This is the maximum maintenance dose. People who reach this dose lose an average 22.5% of their starting weight in 72 weeks.

While it’s beneficial to follow the dosage schedule up to the maximum maintenance dose, as it causes the most weight loss, this does not mean you have to. Tirzepatide is still effective at lower doses, and this depends on how much weight you want to lose and how it works for you.

If you are getting side effects, your doctor may recommend a lower dose for longer, so it might take longer than 21 weeks to reach the maximum maintenance dose.

Tirzepatide maintenance

Tirzepatide is a long-term weight loss treatment, so it can also be taken once you’ve reached your goal weight. This is known as maintenance, and you and your doctor can find a maintenance dose that works for you to keep your weight stable, without losing more. This can be beneficial for people who find it difficult to manage their weight without medication and prevents weight regain from stopping tirzepatide before you're ready.

Tirzepatide is a once-weekly medication, and you should inject it on the same day each week. Before you start using the tirzepatide injection, you should pick which day of the week works best for you. You may find it helpful to set a reminder so you do not forget to take it on your chosen day.

Tirzepatide is designed to be easy to use at home and is supplied in a multi-dose pen (Kwikpen). It comes with a very small needle for minimal discomfort, and the pen is already pre-filled with your doses. You should use tirzepatide for weight loss exactly as your doctor has told you.

Here are the general instructions for using the tirzepatide multi-dose injection pen:

1. Choose your injection site. It should be injected into your stomach, upper arms, or thighs. Rotate the injection site each week or use the right then left side of your body to reduce soreness.
2. Use a new needle for each injection and make sure it’s not unsealed, bent, or damaged. If it is, you should use a new needle.
3. The liquid inside your pen should also be clear and colourless, or have a slight yellow tinge. Otherwise, it should not be used, and you should speak to your doctor or supplier.
4. Once ready, inject your dose into the skin (never a muscle or vein). The needle is very small, so the risk of injecting into the wrong place is very low. Press and hold the button for no more than 10 seconds.
5. When you have finished, you should discard the used needle in your sharps container.

➤ You can find more detailed guidance on using your Mounjaro pen in our Mounjaro injection page.

When is the best time to take tirzepatide?

Tirzepatide can be injected at any time of day, with or without food. You should choose a day and time that is most convenient for you and stick with this throughout treatment.

If you get side effects right after your injection, or if you struggle with needles, it might be better to do it at the end of the day when you can relax at home afterwards. While it does not need to be taken with food, it’s important to eat before it if you have a needle phobia to reduce the chance of feeling faint or dizzy.

Tirzepatide for weight loss is for adults who have a:

• BMI of 30kg/m2 or more
• BMI between 27 and 30kg/m2 and a weight-related health condition, such as high blood pressure, high cholesterol, or prediabetes

It’s suitable for most people, but not if you’re pregnant, breastfeeding, or have an allergy to its ingredients.

These are the guidelines if you’re prescribed tirzepatide through a private service. The NHS has stricter guidelines on who can take tirzepatide due to cost and capacity restrictions. They are currently rolling out tirzepatide over 12 years, starting with those most in need. This means you’ll need to be obese and have 4 out of 5 of these health conditions affected by weight:

• high blood pressure
• type 2 diabetes
• vascular or heart disease
• obstructive sleep apnoea
• high cholesterol

Who can take tirzepatide for diabetes?

Tirzepatide is recommended for people who have unmanaged blood sugar and type 2 diabetes, alongside diet and exercise changes. It is generally prescribed when other diabetes treatments, like metformin, have no effect.

Tirzepatide can cause some side effects, more often very common ones, when you first start treatment, or after a dose increase. While mild in most cases, let your doctor know if they are severe or do not get better.

Very common side effects include:

• feeling sick (nausea)
• being sick (vomiting)
• diarrhoea
• constipation
• low blood sugar, if used alongside other diabetes treatments
• stomach pain

Common side effects include:

• reduced appetite
• indigestion
• low blood pressure
• bloating
• dizziness
• hair loss
• reflux or heartburn
• feeling tired
• fast pulse
• burping or gas
• injection site reactions (itching or redness)
• increased level of pancreatic enzyme lipase in blood
• increased level of calcitonin in blood
• a decrease in appetite
• gallstones

Uncommon side effects include:

• pain at the injection site
• infection of the gallbladder
• gastroparesis (delayed stomach emptying, causing bowel obstruction)
• an inflamed pancreas (acute pancreatitis) – speak to your doctor if you get severe stomach or lower back pain
• an increased level of calcitonin (a hormone that helps to metabolise calcium) in the bloodstream
• fast pulse
• increased levels of the pancreatic enzyme amylase
• change in taste
• skin sensation changes
• delay in stomach emptying

Rarely, tirzepatide can cause a serious allergic reaction. This is a medical emergency, and someone should call 999 straight away. Signs of an allergic reaction include:

• trouble breathing or swallowing
• swelling in the face and airways
• rash
• dizziness or fainting
• Chest pain/tightness, fast heartbeat (palpitations)

Tirzepatide is not suitable for everyone, and you should only take it if your doctor prescribes it to you.

You cannot take tirzepatide if you are:

• under 18
• allergic to any of the ingredients in tirzepatide, including the active and non-active ingredients
• pregnant or breastfeeding

Tirzepatide injection may not be suitable for you if you have a:

• history of pancreatitis, as this condition has developed in some people treated with GLP-1 receptor agonists
• severe gastrointestinal condition
• history of gallstones, as these can develop in some people taking tirzepatide

If you are taking any other prescription, over-the-counter, or herbal remedies, you should tell your doctor before using tirzepatide for weight loss because it may interact with other medicines. You should also let your doctor know if you are taking any other diabetic medications.

Yes, you can buy tirzepatide online from registered online doctor services like Asda Online Doctor by filling in a short medical form about your health, medications, and weight. A doctor can approve your treatment if suitable, which will be delivered to you in discreet packaging. We also provide a weight loss treatment pack and ongoing support through your patient account.

Tirzepatide in the UK for weight loss is only found under the brand name Mounjaro. There is currently no generic.

Is tirzepatide prescription-only?

Yes, tirzepatide is prescription-only which means a doctor must prescribe it to you for weight loss. Over-the-counter tirzepatide does not exist, so be wary of websites offering you tirzepatide or Mounjaro without a prescription, as this is illegal.

Is tirzepatide available on the NHS for weight loss?

Yes, tirzepatide on the NHS is available for people who meet the prescribing guidelines.

How much does tirzepatide cost?

Tirzepatide prices will vary depending on where you get your prescription. Prices for Mounjaro at Asda Online Doctor start at £148.97 for 1 month’s supply. If you get a prescription from the NHS in England, you’ll likely need to pay the current prescription charge.

Please note: these prices were correct at the time of writing but may change. For the most up to date information, check our Mounjaro product page.

Tirzepatide (Mounjaro) and semaglutide (Wegovy) are weekly weight loss injections. The main similarities and differences are shown in this table:

➤ You can also read a more detailed comparison in our tirzepatide vs semaglutide guide.

Is tirzepatide the same as Mounjaro?

Yes, tirzepatide is the active ingredient in Mounjaro. The only medication containing tirzepatide is the branded injection Mounjaro, which can be found for weight loss and type 2 diabetes treatment. There is no generic form currently.

Are there tirzepatide tablets?

No, there are currently no tirzepatide tablets available or any ongoing clinical trials into them. However, Wegovy pill, the oral tablet form of semaglutide (Wegovy), is available and licensed for weight loss in the UK.

Can you microdose tirzepatide?

No, you should not microdose tirzepatide or other weight loss injections. While you can take a lower dose and stay on it, this is not the same as microdosing, which involves taking a very small dose. Mounjaro Kwikpens are made to provide 4 doses of treatment, and are pre-filled with the correct dose. It would be difficult to use the pen in a way other than how it was intended, and doses less than 2.5mg are not likely to provide much of an effect.

Opened pens must also be used within 30 days or thrown away. Microdosing is more likely to waste some of the medication, so you’ll be losing out on effectiveness and money. If you do not want to lose too much weight, or you’re on a budget, you can always stick to a lower dose like 5mg, which is still a maintenance dose and is effective.

Does tirzepatide cause muscle loss?

No, tirzepatide itself does not cause muscle loss. However, rapid weight loss can, especially without the right diet and exercise regime. To reduce the chances of muscle loss as you lose weight, it's important to eat enough protein, and incorporate strength training into your routine, such as weight lifting or resistance training.

How long does tirzepatide last in the fridge?

Unopened, tirzepatide lasts in the fridge until the expiry date. Once opened, tirzepatide lasts 30 days in or out of the fridge. It's important to store Mounjaro properly to make sure it remains effective and safe to use.