There is increasing public interest in weight-loss medications, and in particular, the various injections which can help with this. These medications are known as GLP-1 agonists and include:
Mounjaro (tirzepatide)
Wegovy (semaglutide)
Byetta (exenatide)
There is currently no NHS Lothian service which provides these medications purely for weight-loss purposes. The injections are only available on NHS prescription for people with type 2 diabetes who are under the care of the hospital diabetes team, and where the treatment has been deemed necessary by that team. This is the only situation in which they would be prescribed by GPs in this Practice.
An increasing number of our patients are sourcing weight loss medications privately. Given that this could impact on the NHS care that we provide, we want to ensure that our patients are fully aware of some very important issues surrounding the use of these drugs.
Pregnancy
GLP-1 agonists are NOT safe in pregnancy so it's important to use effective contraception during their use and for a period of time after stopping them (known as a washout period).
The washout period for each of the 3 drugs is:
Mounjaro (tirzepatide) - 1 month
Wegovy (semaglutide) - 2 months
Byetta (exenatide) - 3 months
Contraception
Use of Mounjaro (tirzepatide) reduces the effectiveness of all ORAL contraceptives, i.e. both the combined and progesterone-only types.
Barrier contraception in the form of condoms should be used for 4 weeks after starting Mounjaro, and then for another 4 weeks after each increase in the dosage of the injection. If this is inconvenient, you may want to consider changing to a non-oral form of contraception, such as a coil, or injection. I that's the case, make an appointment and your GP will be happy to arrange that for you.
There is currently no evidence that any of the weight loss drugs other than Mounjaro have this effect on oral contraceptives.
Hormone Replacement Therapy (HRT)
If you are taking a combined oral HRT medication, which contains both progesterone and oestrogen, GLP-1 agonists can affect the absorption of the progesterone component of the HRT. This can affect the ability of the progesterone component to protect the lining of your uterus (the endometrium) from the extra oestrogen you are taking. In some women, this could lead to an increased risk of endometrial cancer.
In order to reduce this endometrial cancer risk, for the duration of the time that you are using any of the GLP-1 agonist injections, you must also take an increased dose of progesterone. The alternative is to switch from an oral HRT to a non-oral form such as a patch or gel, as non-oral forms of HRT are NOT affected by GLP-1 agonists.
If you have recently started a GLP-1 agonist and are taking an oral form of HRT, you should make an appointment with the GP who normally prescribes your HRT so that your treatment can be reviewed.
Further Information on GLP-1 Agonists
For anyone who is obtaining these medicines from a private provider, NHS Lothian has prepared a leaflet which contains information about managing your diet, and any side-effects. The leaflet is available by clicking HERE.