Contraindications and Risk Factors for GLP-1 Use

GLP-1 receptor agonists such as semaglutide, tirzepatide, and liraglutide have transformed the treatment of obesity and type 2 diabetes. They mimic  natural hormones that helps control appetite, digestion, and blood sugar.

Although these medicines are safe and effective for most people, certain medical conditions or risk factors mean they should be used with caution or avoided entirely. This clinical guide outlines those situations to help you understand how doctors decide who is suitable for GLP-1 therapy.

GLP-1 (glucagon-like peptide-1) receptor agonists activate the same pathway as the body’s own GLP-1 hormone.
They slow stomach emptying, reduce hunger, and improve blood-sugar control. Common examples include:

• Semaglutide (Wegovy, Ozempic)
• Tirzepatide (Mounjaro, Zepbound)
• Liraglutide (Saxenda, Victoza)

Because these drugs act through the gut, pancreas, and hormonal pathways, certain health conditions can increase the risk of side effects or complications.

Some situations make GLP-1 receptor agonists unsuitable. Treatment should be avoided if any of the following apply.

Multiple Endocrine Neoplasia type 2 (MEN2)

This rare inherited condition raises the risk of endocrine tumours. GLP-1 receptor agonists are contraindicated in these cases although the link between these medications and these cancers is not certain. It’s better to be safe until we know it is totally  safe to use them in anyone that maybe at risk of this .

Severe gastrointestinal disease (for example, gastroparesis)

Because GLP-1 medicines slow gastric emptying, they can worsen chronic nausea, vomiting, or fullness in people with gut motility problems. It can also cause aspiration as it slows gastric emptying further which may lead to overflow and aspiration.

Risk of DKA

For anyone already taking diabetic medication there is a risk of DKA (diabetic Ketoacidosis.) This is when the body produces ketones which build up in the body over a short period of time due to blood sugar and can be very dangerous. 

Known hypersensitivity

Anyone with an allergy to semaglutide, tirzepatide, liraglutide, or any inactive ingredient should avoid use.

Certain conditions do not rule out treatment but require careful clinical judgment and closer monitoring.

History of pancreatitis

Pancreatitis has occasionally been reported. People with a previous episode should only start GLP-1 therapy after specialist review.

Gallbladder disease

Rapid weight loss can lead to gallstones. Doctors monitor for pain or jaundice during treatment.

Kidney, liver or heart impairment

In r severe kidney disease, hydration and dose adjustment may be needed to protect kidney function. These medications should also be avoided in heart failure and liver disease. 

Gastrointestinal disorders

People with reflux or irritable bowel symptoms may experience stronger side effects. Gradual dose escalation can help tolerance.

Diabetic retinopathy

A sudden drop in blood sugar may make any eye damage from diabetes worse so the advice is not to use this medication with this condition.  

Pregnancy and breastfeeding

GLP-1 medicines are not recommended during pregnancy or breastfeeding. Effective contraception is advised while taking them if there is any risk of pregnancy.

Eating disorders or rapid weight-loss risk

Those with a history of anorexia, bulimia, or restrictive dieting should be managed carefully to avoid relapse.

Psychological distress

Appetite suppression and rapid change in body weight can affect mood. Readiness and support are assessed before starting therapy.

GLP-1 receptor agonists can interact with other drugs or lifestyle factors.

• Insulin or sulfonylureas may increase risk of low blood sugar; dosing should be reviewed.
• Oral contraceptives can have delayed absorption; take at a consistent time each day. We recommend using a different method of contraception whilst taking GLP-1s.
• Other oral medications should be separated from GLP-1 injections if precise timing is important.
• Alcohol and dehydration can worsen nausea or dizziness.
• Very low-carbohydrate diets may heighten fatigue during dose escalation.

Before prescribing, clinicians perform a full assessment that includes:

• Medical and family history
• Review of current medicines and allergies
• Baseline measurements such as weight and BMI 
• Reproductive status and contraception discussion

Medicspot follows NICE and MHRA guidance to ensure every patient receives a safe, evidence-based treatment plan.

Contact a clinician urgently if you experience:

• Severe or persistent abdominal or new back pain
• Continuous vomiting or inability to keep fluids down
• Swelling or lump in the neck, hoarseness, or difficulty swallowing
• Rash, breathing difficulty, or swelling especially around the face
• Sudden vision changes or unexplained fatigue

Never stop GLP-1 medication suddenly without medical advice, as appetite rebound and rapid weight regain can occur.

GLP-1 receptor agonists are highly effective but not appropriate for everyone. Understanding contraindications and risk factors helps ensure treatment is safe and tailored to the individual.

If you are considering GLP-1 therapy, complete a clinical assessment to confirm eligibility and discuss any medical concerns with a qualified clinician.

Dr Abby Hyams completed her medical training in Bristol and has been a GP for 19 years, spending many of those as a partner in an NHS practice in Hemel Hempstead. She has a particular passion for supporting patients with weight loss and promoting positive behaviour change, helping individuals build sustainable habits that improve their long-term health and wellbeing.

This article is for general information only and should not be used for the diagnosis or treatment of medical conditions. Medic Spot Limited has used all reasonable care in compiling the information but makes no warranty as to its accuracy. Consult a doctor or other healthcare professional for diagnosis and treatment of medical conditions. In the event of an emergency, please call 999 for immediate assistance.

There is no guarantee of a specific weight loss medication being prescribed. Clinicians will review your online questionnaire alongside other independently validated medical information about you and will recommend the most appropriate weight loss treatments for you based on your answers. In some cases, the clinicians may contact you for additional information. See Terms of Service for more information.