Weight loss medications

Acceptability at Recruitment

QUALIFIED

Acceptability at VT / Work-Up

QUALIFIED

Naltrexone–bupropion (Mysimba) – DISCUSS with MO

Individual at Risk

Donor

Explanation of Condition

GLP-1 agonists were originally developed for the treatment of diabetes. A notable side effect observed during their use was weight loss. In recent years, their application has expanded to include non-diabetic patients, specifically for weight management and obesity treatment.

Commonly used medications in this class are Ozempic, Wegovy, Mounjaro, and Saxenda. The names of the active medications are semaglutide, tirzepatide, and liraglutide. Liraglutide (Saxenda) and semaglutide (Wegovy) are available on the NHS.

Orlistat is a tablet medication that works by decreasing the amount of fat absorbed from food, and can be prescribed via the NHS.

Rybelsus is an oral GLP-1 agonist which is available off-license. Wegovy Pill (Oral Semaglutide 25 mg) is also now licensed by the MHRA for weight management as a once-daily tablet. It is available via private prescription providers, though not yet funded or widely offered through the NHS.

Naltrexone–bupropion (Mysimba) works by decreasing appetite and cravings. It is not available via the NHS.

Guidance

Guidance at recruitment

Acceptable

Guidance at VT

The use of weight loss medications is generally acceptable, but the following steps should be taken:

Medical history

• Ask the patient whether they have a diagnosis of type 2 diabetes. If the GLP-1 medication is also being used to control diabetes, please see the Diabetes Mellitus page, it is not acceptable to ask donors to hold medications controlling their diabetes.
• Check donor's current BMI and refer to the corresponding guidelines in the Weight section. A donor’s BMI is likely to fall when taking GLP-1 agonists, so it may be appropriate to make the donor TU for a period if their BMI is currently above our discretionary limits and check it has not fallen during the process for accurate weight based dosing prescribing.
• Determine whether the donor is experiencing any significant side effects related to their current medication regimen. Common side effects include nausea and stomach upset. If the donor is experiencing unpleasant side effects, defer the donation until they have resolved, or the donor ceases the medication.

Source of medication

• Weight loss medications can be accessed through the NHS, but they are often obtained privately.

• If the donor has acquired the medication from an online pharmacy, confirm that the service is properly registered (e.g. General Pharmaceutical Council (GPhC)).

You can also check registration status through NHS resources: https://www.nhs.uk/service-search/other-health-services/pharmacies/internetpharmacies

• If an injectable weight loss drug has been obtained from an unverified or non-legitimate source, apply a deferral period of three months between the last injection date and the donation should apply but this may be reduced at the discretion of the MO and TC.

• For non-injectable weight loss drugs (i.e. in tablet form) obtained from an unverified source, discuss with MO.

• Naltrexone–bupropion (Mysimba) – discuss with MO even if the medication has been obtained from a reliable source.

Bone marrow harvests

Donors taking weight loss injections are suitable for a bone marrow harvest. However, a washout period should be undertaken between the last dose of the weight loss medicine and for the donation. For injections this should be 2 weeks and may be one or two doses. For oral medication this can be more variable and would need to be flagged to the anaesthetist in advance.

For an emergency bone marrow harvest where holding a medication dose is not possible, the decision to proceed is undertaken on a risk-benefit basis after discussion with the donor. This decision would be undertaken by the anaesthetist.

Donors taking GLP-1 medication for diabetic control also should not stop this medication, and should only be for PBSC donation only.

Justification

Since GLP-1 agonist injections are administered subcutaneously, it is essential to verify that the medication has been sourced from a reputable supplier due to the risk of needle-transmitted blood borne viruses.

Naltrexone–bupropion (Mysimba) interacts with some painkillers and anaesthetic drugs. Therefore, any donor taking this medication should be discussed with an MO.

Weight loss medications increase anaesthetic risk due to the risk of aspiration secondary to reduced gut motility. Bone marrow donors taking these drugs may require longer pre-operative periods of fasting than would otherwise be the case, so anaesthetics staff must be informed well in advance of the planned date of bone marrow harvest

Version

Version 1, Edition 2

Date of Last Update

2nd July 2025 29th October 2026