Absolute contraindications to GLP-1 therapy
The situations in which GLP-1 medicines must not be used, and the safer alternatives we discuss instead.
Written by Professor Mohammed Mahdi Althaf
Medically reviewed by Professor Mohammed Mahdi Althaf, Consultant Nephrologist · 3 August 2026
Overview
While GLP-1 medications are safe for most, there are certain medical conditions where they are strictly prohibited (absolute contraindications). At The Kidney Weight Clinic, safety is our first priority, adhering to MHRA and BOMSS safety standards.
Who it helps (by keeping them safe)
- Personal or Family History of Medullary Thyroid Carcinoma (MTC): These medications are not suitable for anyone with this rare type of thyroid cancer.
- Multiple Endocrine Neoplasia syndrome type 2 (MEN 2): A genetic condition that predisposes to certain tumours.
- Pregnancy and Breastfeeding: GLP-1s must be stopped at least two months before trying to conceive, as per NICE and manufacturer guidance.
- Previous Severe Hypersensitivity: Any past allergic reaction to these medications.
NICE and British Obesity Guidance
- NICE guidelines and BOMSS (British Obesity & Metabolic Surgery Society) standards stipulate that these contraindications must be screened for at the initial assessment.
- Professor Mohammed Mahdi Althaf conducts a full clinical history review at your first face-to-face appointment to ensure absolute safety.
"Beyond the Injection" — Alternative Paths
If you have a contraindication, we will discuss alternative weight management strategies, such as renal-specific nutritional therapy guided by Renal Association dietitians or referral for bariatric surgery assessment.
Preparing for your appointment
I have a different type of thyroid cancer — can I start?
Usually, yes. Only Medullary Thyroid Carcinoma (MTC) is a contraindication.
What if I get pregnant?
Stop the medication immediately and contact the clinic. We will help you transition to a safe pregnancy weight management plan.
References
- NICE TA875: Semaglutide for managing overweight and obesity
- British Obesity & Metabolic Surgery Society (BOMSS) Standards
- MHRA Drug Safety Update: GLP-1 Receptor Agonists
This article is general patient information reviewed by a consultant nephrologist. It is not individual medical advice; treatment decisions are made at a face-to-face consultation.