Tirzepatide (Mounjaro)

Generic name

Tirzepatide (Mounjaro)

Active ingredient

Tirzepatide (Mounjaro)

Product type

Small-molecule medicine

Drug class

GLP-1 receptor agonists

Brand names

UK Mounjaro

Routes

Subcutaneous

Dosage forms

Pen injector

Also known as

Mounjaro

Monitoring

NICE says that if too little of the starting weight has been lost after six months at the highest tolerated dose, the prescriber decides whether to continue, weighing the benefits and risks for that person.

Availability by country

Legal status differs between countries and can change; each row cites the document it was taken from and applies only to the country named.

What it is used for

• Managing type 2 diabetes in adults who meet NICE criteria, alongside diet and exercise
• Treating overweight and obesity in adults, alongside a reduced-calorie diet and more physical activity as part of a weight management programme

How it works in the body

Tirzepatide activates the receptors for two gut hormones, GLP-1 and GIP, so it is called a dual agonist. For weight loss, the NHS says it reduces appetite and helps people feel fuller for longer. For type 2 diabetes, it lowers blood sugar and helps the body make more insulin when needed.

Cautions and interactions

• May not suit people who have had an allergic reaction to tirzepatide or a similar GLP-1 medicine, or who have had acute pancreatitis
• The MHRA says GLP-1 medicines may reduce how well oral contraceptives work in people who are overweight or obese, and advises a non-oral method in addition to the pill for people who are overweight and taking Mounjaro
• The NHS says it is not used in pregnancy because there is not enough information about its effects on a baby; the MHRA says GLP-1 medicines should not be taken during pregnancy, while trying to get pregnant or during breastfeeding
• Low blood sugar is more likely with other diabetes medicines
• The NHS says it is best to avoid alcohol, which can increase side effects such as feeling or being sick

Interactions

Interactions documented in the official sources cited on each card. The list covers the medicines represented on this site and is not exhaustive; how the interaction data is compiled.

No pair records for this medicine are in the sources currently represented by Anatomy Nexus. Absence from this list does not mean no interaction exists.

Same-class and related medicines

Same class: GLP-1 receptor agonists

Medicines that share the class of Tirzepatide (Mounjaro). They are separate medicines with their own licences, doses and interactions, not alternative names for Tirzepatide (Mounjaro).

Related medicines

Medicines often discussed alongside Tirzepatide (Mounjaro): used together, compared with it, or acting on the same problem by a different route.

Key facts

What is tirzepatide used for?

Tirzepatide is a prescription medicine used to manage type 2 diabetes and to treat obesity. In the UK it is sold under the brand name Mounjaro. It is an injection that people give themselves.

NICE has recommended tirzepatide for some adults with type 2 diabetes who meet set criteria, alongside diet and exercise. NICE has also recommended it as an option for adults with overweight or obesity, alongside a reduced-calorie diet and more physical activity. NICE links this to a person's starting body mass index and to having at least one weight-related health condition. NICE applies a lower body mass index threshold for people from some ethnic backgrounds.

For weight management, the NHS says tirzepatide is only prescribed alongside programmes that support changes to diet and physical activity.

How does tirzepatide work?

Tirzepatide activates the receptors for two gut hormones, GLP-1 and GIP, so it is called a dual agonist. For weight loss, the NHS says it reduces appetite and helps people feel fuller for longer. For type 2 diabetes, it lowers blood sugar and helps the body make more insulin when needed. An NHS medicines optimisation newsletter adds that it increases insulin secretion, suppresses glucagon release and slows the emptying of the stomach.

NICE says it can be used in primary care or in specialist weight management services. Access on the NHS in England is being phased in, so not everyone who fits the NICE recommendation can have it at once. NHS England's interim commissioning guidance sets out which groups are offered it first.

What side effects can tirzepatide cause?

The NHS lists feeling sick and being sick among the common side effects. It also lists constipation, diarrhoea, stomach pain, tiredness, hair loss and redness at the injection site. The NHS says most serious side effects are rare.

The NHS lists inflammation of the pancreas (acute pancreatitis), which can cause severe pain in the stomach or back that does not go away, as a serious side effect. The NHS also lists gallstones or swelling of the gallbladder, which can cause severe tummy pain. A serious allergic reaction (anaphylaxis) can cause a swollen throat or tongue, a raised itchy rash or difficulty breathing. Severe pain that does not go away needs urgent advice from NHS 111 or the GP, and signs of a serious allergic reaction are an emergency that needs a 999 call.

The NHS lists low blood sugar, which is more likely when tirzepatide is used with other diabetes medicines and can cause headaches, vision problems, feeling dizzy, weak or confused, a fast heartbeat or sweating.

Tirzepatide with contraception, alcohol and other medicines

The MHRA says GLP-1 medicines may reduce how well oral contraceptives work in people who are overweight or obese. For people who are overweight and taking Mounjaro, the MHRA advises using a non-oral method of contraception in addition to the pill. The MHRA lists the pill and non-oral methods such as the implant, coil or condoms as effective contraception.

The NHS says it is best to avoid alcohol, because alcohol can increase side effects such as feeling or being sick. Low blood sugar is more likely when tirzepatide is combined with other diabetes medicines.

Who needs extra care with tirzepatide?

The NHS says most adults can use tirzepatide. It may not suit people who have had an allergic reaction to tirzepatide or a similar GLP-1 medicine, or who have had acute pancreatitis.

The NHS says tirzepatide is not used in pregnancy because there is not enough information about its effects on a baby. The MHRA says GLP-1 medicines should not be taken during pregnancy, while trying to get pregnant or during breastfeeding, because of a lack of human data. The MHRA also advises that people who could become pregnant take steps to avoid pregnancy while using GLP-1 medicines. The NHS says it is not known whether tirzepatide passes into breast milk.

NICE says that if too little of the starting weight has been lost after six months at the highest tolerated dose, the prescriber decides whether to continue, weighing the benefits and risks for that person.

Frequently asked questions