Health authorities have issued urgent new safety warnings for a popular class of weight loss and diabetes drugs, following reports linking them to serious mental health risks and contraceptive failure. Medications containing semaglutide, such as Ozempic and Wegovy, and tirzepatide, found in Mounjaro, are under increased scrutiny.
Analysing the Link to Suicidal Thoughts
The Therapeutic Goods Administration (TGA) in Australia issued the alert this week, highlighting potential dangers. Analysis of adverse event reports identified 20 cases of suicidal thoughts coinciding with the use of a GLP-1 medicine in the 12 months to November 2025.
This finding aligns with some international research. A significant 2024 study indicated these drugs could be associated with a 106 per cent increase in the risk of suicidal behaviour. Further analysis of World Health Organisation data also pointed to a connection between semaglutide use and suicidal ideation.
However, the scientific picture is not entirely clear. A separate, large-scale 2024 study involving data from over 1.8 million patients found the opposite. It concluded that patients taking GLP-1 medicines for weight loss or diabetes actually had a lower risk of new or recurring suicidal thoughts compared to those not on the drugs.
How Weight Loss Jabs Can Affect Contraception
Perhaps more definitively, the warnings also cover a serious risk regarding oral contraceptive pills. Evidence suggests GLP-1 drugs can interfere with the body's absorption of the hormones in these contraceptives, potentially rendering them less effective and leading to unwanted pregnancies.
This risk was first flagged by researchers back in 2003. The impact appears to vary between different GLP-1 medicines. A review found that tirzepatide (Mounjaro) had a higher impact on hormone absorption compared to others in the class.
While a 2015 study on semaglutide found no effect on common contraceptive hormones, a more recent 2025 study concluded that both tirzepatide and oral semaglutide could affect hormone levels. It is important to note that non-oral contraceptives like implants or IUDs are not affected, as they do not rely on stomach absorption.
What Patients in the UK Need to Do Now
For individuals currently using these medications, the TGA's recommendations are clear. Patients should immediately inform their doctor if they experience new or worsening depression, suicidal thoughts, or any unusual changes in mood or behaviour.
For women using tirzepatide (Mounjaro) alongside oral contraceptives, specific advice is given. The TGA advises either switching to a non-oral contraceptive method or adding a barrier method, like condoms, for four weeks after starting the drug or increasing the dose.
A critical warning states that GLP-1 drugs should not be used during pregnancy, as they may affect fetal growth. The adverse events database has recorded cases of miscarriage in women taking semaglutide or tirzepatide.
If you are struggling with your mental health, support is available. In the UK and ROI, you can contact the Samaritans confidentially on 116 123 or via email at jo@samaritans.org.
