Many women with type 2 diabetes or obesity wonder whether GLP-1 receptor agonists—such as semaglutide, liraglutide, or dulaglutide—are safe whilst breastfeeding. These medications, increasingly prescribed for glycaemic control and weight management, raise important questions for new mothers requiring ongoing metabolic treatment. Current UK guidance from the MHRA, NICE, and manufacturers' product information consistently advises against using GLP-1 medications during lactation due to insufficient safety data. This article examines the evidence, explores alternative management options compatible with breastfeeding, and clarifies when to seek medical advice to ensure both maternal and infant wellbeing.

What Are GLP-1 Medications and How Do They Work?

Glucagon-like peptide-1 (GLP-1) receptor agonists are a class of medications primarily used to manage type 2 diabetes mellitus and, more recently, obesity. These medicines mimic the action of naturally occurring GLP-1, a hormone produced in the intestine that plays a crucial role in glucose regulation and appetite control.

The mechanism of action involves several physiological processes. GLP-1 receptor agonists stimulate insulin secretion from pancreatic beta cells in a glucose-dependent manner, meaning they only promote insulin release when blood glucose levels are elevated. This reduces the risk of hypoglycaemia compared with some other diabetes medications. Simultaneously, these agents suppress glucagon secretion, a hormone that raises blood glucose, thereby further improving glycaemic control. Additionally, GLP-1 medications slow gastric emptying, which helps moderate post-meal blood glucose spikes and promotes satiety.

Commonly prescribed GLP-1 receptor agonists in the UK include:

• Semaglutide (Ozempic, Wegovy, Rybelsus [oral formulation])

• Dulaglutide (Trulicity)

• Liraglutide (Victoza, Saxenda)

• Exenatide (Byetta [twice-daily], Bydureon [weekly])

• Tirzepatide (Mounjaro) - a dual GIP/GLP-1 receptor agonist with similar considerations

These medications are typically administered via subcutaneous injection (daily, twice-daily or weekly depending on the specific formulation), with semaglutide also available as an oral tablet. GLP-1 receptor agonists have demonstrated glycaemic control, cardiovascular benefits in certain patient populations and significant weight reduction effects.

Understanding how these medications work helps contextualise the precautions surrounding their use during lactation for new mothers requiring ongoing metabolic management.

Current UK Guidance on GLP-1 Use During Lactation

Current evidence regarding GLP-1 receptor agonist safety during breastfeeding is extremely limited, and UK regulatory guidance is clear: these medications should not be used during breastfeeding. The Medicines and Healthcare products Regulatory Agency (MHRA) and manufacturers' Summaries of Product Characteristics (SmPCs) consistently advise against using GLP-1 receptor agonists whilst breastfeeding due to insufficient data on excretion into human breast milk and potential effects on nursing infants.

Animal studies have shown that GLP-1 analogues and their metabolites can be detected in milk, though the relevance to human lactation remains unclear. There is no official link established between GLP-1 use and specific adverse effects in breastfed infants, primarily because robust human studies have not been conducted. The theoretical concerns centre on the potential for these large peptide molecules to affect infant growth, glucose metabolism, or gastrointestinal function, though the extent of oral bioavailability following ingestion in breast milk is uncertain.

NICE guidance on diabetes management does not endorse GLP-1 receptor agonists for breastfeeding women. The British National Formulary (BNF) reflects the manufacturers' advice that these medications should not be used during lactation. This cautious approach reflects the precautionary principle applied when safety data are lacking rather than evidence of actual harm.

For women with type 2 diabetes who were taking GLP-1 medications before pregnancy, discontinuation is recommended before conception or as soon as pregnancy is confirmed. For semaglutide specifically, the SmPC advises discontinuation at least 2 months before a planned pregnancy due to its long half-life. Alternative diabetes management strategies should be employed throughout pregnancy and the postnatal period. Healthcare professionals must weigh the maternal need for glycaemic or weight control against the theoretical risks to the infant, recognising that uncontrolled diabetes itself poses significant health risks to the mother.

Alternative Diabetes and Weight Management Options for Breastfeeding Mothers

Breastfeeding women requiring diabetes management or weight control have several evidence-based alternatives that are considered safer during lactation. The choice of treatment depends on individual circumstances, diabetes type, glycaemic control, and maternal health priorities.

For type 2 diabetes management, NICE guidance (NG3) recommends the following options during breastfeeding:

• Metformin: This first-line oral medication is extensively studied during lactation. Only minimal amounts pass into breast milk, and it is considered safe for nursing infants. Metformin helps improve insulin sensitivity and glycaemic control without causing hypoglycaemia.

• Insulin therapy: All types of insulin (rapid-acting, short-acting, intermediate, and long-acting) are safe during breastfeeding. Insulin molecules are too large to pass significantly into breast milk, and any that do would be digested in the infant's gastrointestinal tract. Insulin remains the gold standard for diabetes management when oral agents are insufficient.

Other oral antidiabetic medications, including SGLT2 inhibitors and DPP-4 inhibitors, are generally not recommended during breastfeeding due to limited safety data. Glibenclamide may occasionally be considered under specialist supervision when other options are unsuitable, with careful monitoring of the infant for signs of hypoglycaemia (poor feeding, jitteriness, unusual sleepiness).

For weight management, non-pharmacological approaches are strongly recommended:

• Dietary modification: Working with a registered dietitian to develop a balanced eating plan that maintains adequate nutrition for milk production

• Physical activity: Gradual return to exercise as appropriate postpartum

• Behavioural support: Structured weight management programmes that address lifestyle factors

Breastfeeding itself supports metabolic health and gradual postpartum weight loss. The NHS advises that women avoid restrictive dieting whilst breastfeeding, aiming instead for gradual, sustainable weight reduction. Weight management medications (including GLP-1 receptor agonists and orlistat) should generally be deferred until after weaning, unless exceptional circumstances warrant earlier intervention with careful risk-benefit assessment by specialists.

If you experience any side effects from diabetes medications, report them through the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk).

When to Speak with Your GP About GLP-1 and Breastfeeding

Proactive communication with your GP or diabetes specialist team is essential if you are taking or considering GLP-1 medications whilst breastfeeding or planning to breastfeed. Several scenarios warrant prompt medical consultation to ensure both maternal and infant safety.

You should contact your healthcare provider if:

• You are currently taking a GLP-1 medication and discover you are pregnant or planning to breastfeed: Early discussion allows time to transition to safer alternatives before delivery.

• Your diabetes control is deteriorating postpartum: If blood glucose levels are consistently elevated despite current management, your GP can review treatment options compatible with lactation rather than restarting GLP-1 therapy.

• You are experiencing significant weight-related health complications: Conditions such as severe obesity with comorbidities may require individualised risk-benefit assessment regarding pharmacological intervention.

• You are considering stopping breastfeeding to resume GLP-1 treatment: This decision should be made collaboratively, considering the benefits of continued breastfeeding against maternal health needs.

Seek urgent medical attention if you experience symptoms of very high blood glucose (glucose >20 mmol/L, excessive thirst, frequent urination, fatigue), positive ketones in urine or blood, vomiting, abdominal pain, drowsiness, dehydration, or rapid breathing. These could indicate diabetic ketoacidosis or severe hyperglycaemia requiring immediate treatment.

During your consultation, be prepared to discuss:

• Your current diabetes control and any home blood glucose monitoring results

• Previous medication history and responses to different treatments

• Your breastfeeding intentions and duration goals

• Any family history of diabetes or metabolic conditions

• Lifestyle factors including diet, physical activity, and weight changes

Your GP may arrange:

• HbA1c testing to assess overall glycaemic control

• Referral to a diabetes specialist nurse or consultant endocrinologist

• Dietitian consultation for medical nutrition therapy

• Postnatal diabetes review if you had gestational diabetes

Remember that uncontrolled diabetes poses significant risks including cardiovascular disease, neuropathy, retinopathy, and nephropathy. Effective management during the breastfeeding period protects your long-term health whilst supporting your infant's nutrition. Never discontinue prescribed diabetes medications without medical supervision, as abrupt changes can lead to dangerous glucose fluctuations. Your healthcare team can develop a personalised management plan that balances maternal metabolic health with infant safety throughout the lactation period and beyond.

Frequently Asked Questions