Suicidal thoughts, depression: WHO flags shocking side effects of weight loss drugs

New Delhi: The global demand for GLP-1 medicines, such as Ozempic, Wegovy, and Mounjaro, shows no signs of slowing. Originally intended for diabetes management, these injections have found a massive secondary market in weight loss, reshaping everything from medical guidelines to Hollywood red-carpet routines. Alongside stories of dramatic transformations, however, doctors are now flagging two emerging concerns: a possible rise in suicidal thoughts and unexpected pregnancies linked to oral contraception failures. As prescriptions climb, so do the questions. What do we actually know about these risks — and what should patients do?

GLP-1 drugs mimic a naturally occurring hormone that regulates blood sugar and appetite. In Australia, five medicines in this class are approved: Mounjaro (tirzepatide), Ozempic and Wegovy (both semaglutide), Saxenda (liraglutide) and Trulicity (dulaglutide).

Although these injections have been available for years, the recent boom in off-label weight-loss use has taken them mainstream. The side effects most people notice are gastrointestinal — nausea, vomiting, constipation, and abdominal discomfort. Usually, these settle over time. But safety regulators are now paying closer attention to more serious, less-understood risks.

Investigating Suicidal Thoughts

In the past year, Australia’s Therapeutic Goods Administration recorded 20 reports of suicidal ideation occurring while patients were on GLP-1 medications. These individual cases alone don’t establish cause and effect, but they mirror patterns seen in scientific research.

A 2024 study reported a more than twofold (106%) increase in suicidal behaviour among GLP-1 users. Data from the World Health Organization also noted possible links between semaglutide and suicidal thoughts. Yet the picture remains far from settled. Another major study in the same year, involving over 1.8 million patients, found the opposite: people taking GLP-1 drugs had lower rates of new or recurring suicidal thoughts compared to those who were not. Researchers say the conflicting results highlight just how complex the issue is — and why monitoring symptoms closely remains essential.

Do weight loss drugs cause infertility?

The second concern is about oral contraceptives. These pills help prevent a pregnancy by releasing hormones that thicken cervical mucus and inhibit ovulation. However, for them to work, the body must absorb hormones at a reliable, steady rate. Because GLP-1 drugs slow digestion, they may also slow — or reduce — the absorption of contraceptive hormones. This theory isn’t new. Researchers first raised questions about the interaction in 2003. More recently, tirzepatide has drawn particular attention: a review found it produced a noticeable drop in hormone absorption when taken with oral contraceptives.

Semaglutide appears to behave differently. A 2015 study found no meaningful change in hormone levels among women taking common contraceptive pills alongside the drug. However, as per research published in 2025, semaglutide and tirzepatide can influence hormone concentration enough to raise the risk of unintended pregnancy. Crucially, these effects apply only to oral contraceptives. Long-acting methods such as IUDs and implants should continue to work normally because they don’t rely on stomach absorption.

What Should Patients Do?

The TGA’s latest guidance urges anyone on GLP-1 medications to seek medical advice immediately if they notice worsening mood, depression, or thoughts of self-harm. Doctors may adjust dosage, add monitoring, or recommend alternative therapies.

For women using tirzepatide and relying on the pill, the advice is clearer. The TGA recommends:

Switching to a non-oral contraceptive, such as an implant or IUD, or using a backup barrier method for four weeks after starting tirzepatide or after any dose increase. Pregnancy while on a GLP-1 drug is strongly discouraged. Studies also suggest that the medication can interfere with fetal development, and according to data from Australia, miscarriage is also a possibility.

The World Health Organization (WHO) has taken a major step in addressing the worldwide rise in obesity by issuing its first-ever guidance on the use of medications for long-term weight management. The same comes at a time when the world is struggling with an obesity crisis globally. At present, over a billion people in the world are struggling with obesity, and as of 2024, it resulted in 3.7 million deaths. The number is likely to inflate unless proper steps are taken to combat the same; in such a scenario, weight loss drugs were introduced. But little did one know that the downside could be much worse.

Citing this, the WHO has issued new recommendations centered on GLP-1 drugs, first introduced to treat type 2 diabetes. In the past few years, these have helped with blood sugar control, weight loss, and appetite regulation. But WHO stresses that these drugs are only one piece of a larger approach. According to Director-General Dr. Tedros Adhanom Ghebreyesus, obesity "is a lifelong condition,” and medication works best when paired with healthier eating patterns, increased physical activity, and ongoing clinical support.

What the New Guidance Covers

The recommendations focus on adults—excluding pregnant women—who are considering GLP-1 therapy as part of a long-term strategy to manage obesity. Because comprehensive data on extended use are still emerging, WHO classifies the guidance as conditional. Questions remain regarding the durability of weight loss after discontinuing the drugs, their safety over many years of use, and how access to them might vary between countries with differing healthcare resources.

WHO emphasizes that medication should not replace lifestyle programs. Clinical evidence consistently shows that people have better long-term outcomes when pharmacological treatment is combined with structured nutrition plans, regular exercise, and practical behavioral support. The programs can help people sustain their progress and prevent fat re-accumulation.

WHO's 3-part strategy

Obesity causes more damage than just one's appearance - there is a risk of heart diseases, chronic and acute lifestyle disorders, and even cancer in some cases. To address the same issue, the WHO has shared a three-part strategy.

WHO also estimates that less than one in ten people, who are likely to benefit from GLP-1 medicines, will have access to them by 2030. This can lead to an increase in health disparities.