GnRH antagonist medications like Myfembree and Ryeqo — what are the mental health side effects, and how long is it safe to take them?
Many people taking GnRH antagonist medications describe exactly this feeling. The mood changes can be subtle at first — low energy, emotional flatness, a loss of interest in things that used to matter. For others, the shift is sharper and more frightening. Understanding what these medications actually do to your hormones, and what your prescriber should have told you before you started, is the first step to making sense of what happened.
A common pattern — where care can break down with GnRH antagonist therapy
GnRH antagonist medications are relatively new in their current oral form. Myfembree (relugolix, estradiol, and norethindrone acetate) and Ryeqo (the same combination, marketed under a different name in some regions) suppress the body’s production of oestrogen and progesterone. Doctors prescribe them primarily for endometriosis and uterine fibroids.
Because these medications are newer, prescribing patterns are still developing. Several failure patterns appear repeatedly in patient experiences.
Prescribing without a mental health history review
A prescriber should ask about a patient’s history of depression, anxiety, or mood disorders before starting a GnRH antagonist. Hormonal suppression can worsen pre-existing mental health conditions. When a prescriber skips this step, a patient with a history of depression may start a medication that significantly lowers their mood — without any warning that this risk exists for them specifically.
No baseline mood assessment before starting
Best practice involves documenting how a patient feels before they start the medication. Without a baseline, neither the patient nor the prescriber can clearly identify whether a mood change is new, worsening, or unrelated to the drug. Many patients report that nobody asked them how they were feeling emotionally before they started.
Inadequate informed consent about psychiatric side effects
The product information for these medications lists mood changes, depression, and in some cases suicidal ideation as known adverse effects. Informed consent — the process by which a doctor explains the risks of a treatment before a patient agrees to it — requires that a prescriber discuss these risks in a way the patient can understand. Handing over a printed leaflet does not satisfy this obligation. Many patients report they were told about hot flushes and bone density but nothing about mood or suicidal thoughts.
No follow-up review scheduled
These medications require active monitoring. A prescriber who issues a repeat prescription without scheduling a review appointment — or whose clinic fails to follow through when a review appointment lapses — leaves the patient without the safety net the medication requires. The Australian Commission on Safety and Quality in Health Care sets clear expectations around medication safety and ongoing patient monitoring in Australian clinical settings.
Prescription lapsing without contact
Some patients describe a situation where their review appointment fell through — the clinic rescheduled, the GP was unavailable, or the system simply did not follow up — and their prescription lapsed. Stopping a GnRH antagonist abruptly can cause a rapid hormonal shift. That shift carries its own risks, including a sudden return of symptoms and potential mood destabilisation.
Understanding GnRH antagonist medications — what they are and what they do
GnRH stands for gonadotropin-releasing hormone. Your brain normally releases this hormone to signal your ovaries to produce oestrogen and progesterone. A GnRH antagonist blocks that signal. The result is a rapid and significant drop in oestrogen and progesterone levels.
Doctors use this suppression to treat conditions that are driven by oestrogen — particularly endometriosis (a condition where tissue similar to the uterine lining grows outside the uterus) and uterine fibroids (non-cancerous growths in the uterus). By lowering oestrogen, the medication reduces the growth and activity of these tissues, which can reduce pain and bleeding.
What makes the add-back component important
Myfembree and Ryeqo are combination medications. They include a low dose of oestrogen and a progestogen alongside the GnRH antagonist. This is called “add-back therapy.” The idea is to suppress oestrogen enough to treat the condition, while adding back just enough to reduce side effects like hot flushes and bone density loss.
The add-back component does not fully prevent all side effects. Oestrogen levels on these medications remain significantly lower than normal. That matters because oestrogen plays a role in brain chemistry — including the regulation of serotonin, a chemical involved in mood.
What the medication does: Blocks the brain’s signal to the ovaries, rapidly lowering oestrogen and progesterone.
Why add-back therapy is included: To partially offset side effects from very low oestrogen, including bone loss and vasomotor symptoms (hot flushes, night sweats).
How long these medications are approved for: In Australia, current approvals are generally for up to 24 months. Long-term use beyond this requires careful clinical review.
Who should be especially cautious: People with a personal or family history of depression, anxiety, or other mood disorders face a higher risk of psychiatric side effects.
For more general information about hormonal medications and their effects, Healthdirect Australia provides accessible, evidence-based health information for Australian patients.
When things start to go wrong — recognising the mental health side effects
The mental health side effects of GnRH antagonist medications are real, documented, and listed in the product information for both Myfembree and Ryeqo. Many patients do not know this because nobody told them before they started.
The side effects most commonly reported include:
- Low mood or persistent sadness
- Emotional flatness — feeling disconnected or numb
- Anxiety or increased irritability
- Reduced libido (sex drive)
- Difficulty sleeping
- Cognitive changes — difficulty concentrating or remembering things
- Depressive episodes
- In some cases, suicidal thoughts or ideation
If you are experiencing suicidal thoughts: Please reach out to Lifeline on 13 11 14 (available 24 hours) or go to your nearest emergency department. These thoughts can be a direct effect of hormonal suppression — they are a medical symptom, not a personal failing.
Signs that require urgent review with your prescriber:
• Any new or worsening thoughts of self-harm or suicide
• A significant and sudden change in mood that appeared after starting or changing the dose
• Feeling unable to function day-to-day in ways that were not a problem before starting the medication
• Mood changes that your prescriber has dismissed or attributed to something else
Not everyone experiences these effects. Some people tolerate GnRH antagonists well and find significant relief from their underlying condition. But the risk is real enough that it requires active discussion before a patient starts the medication — and active monitoring while they are on it.
Why oestrogen suppression affects mood
Oestrogen influences the brain’s serotonin system. Serotonin is a neurotransmitter — a chemical messenger — that plays a central role in regulating mood, sleep, and emotional stability. When oestrogen drops sharply, serotonin activity can also change. For people who already have a vulnerability to depression or anxiety, this shift can tip them into a clinical episode. For people with no prior history, it can still cause meaningful mood disruption.
Why this matters legally
A doctor who treats you owes you a duty of care. That means they have a legal obligation to provide treatment that meets the standard a competent clinician in their field would provide. When a prescriber fails to meet that standard, and that failure causes you harm, the law may recognise this as medical negligence.
Medical negligence (sometimes called clinical negligence) is not about a bad outcome. Not every side effect is negligence. Some people experience mood changes on GnRH antagonists even when their prescriber did everything correctly. The legal question is different: did the prescriber take the steps a reasonable, competent clinician would have taken — and if not, did that failure cause harm that would not otherwise have occurred?
In the context of GnRH antagonist therapy, the legal issues most likely to arise involve informed consent and monitoring failures — not the medication itself. For a fuller explanation of how medical negligence works in Australia, see Reframe Legal — Medical Negligence.
Experiencing mood changes despite receiving a full warning and regular monitoring — some side effects occur even with proper care
Developing a serious depressive episode or suicidal crisis after a prescriber failed to warn about psychiatric risks, failed to review a known mental health history, or allowed a prescription to lapse without follow-up
This is a general educational framework only. Each case is assessed on its individual facts.
When GnRH antagonist prescribing may amount to medical negligence
The NSW Civil Liability Act 2002 is the main law governing medical negligence claims in New South Wales. It sets out the standard a clinician must meet and the test for whether a failure caused harm. Under this framework, several specific scenarios involving GnRH antagonist therapy may give rise to a legal claim.
Failure to warn about psychiatric side effects
If a prescriber did not tell you that mood changes, depression, or suicidal ideation are known side effects of this medication — and you later experienced one of those effects — the prescriber may have failed their informed consent obligation. A patient who knows the risk can make a different choice. A patient who does not know cannot.
Prescribing without reviewing mental health history
A clinician who prescribes a medication known to affect mood without first asking about a patient’s psychiatric history has skipped a basic clinical step. If that patient then experiences a serious mental health episode, the failure to review their history may be directly relevant to what happened.
Failure to monitor during treatment
Prescribing a GnRH antagonist is not a one-time event. The medication requires ongoing review. A prescriber who issues repeat prescriptions without scheduling or conducting mood assessments may have failed to meet the monitoring standard these medications require.
Allowing a prescription to lapse without follow-up
A patient whose review appointment was not followed through — and whose prescription then lapsed — may have experienced an abrupt hormonal shift with no clinical support. If the clinic or prescriber knew the appointment had not occurred and took no action, that failure may be relevant to any harm that followed.
When harm becomes long-term or permanent
For most people, mood-related side effects from GnRH antagonists resolve after stopping the medication. But for some, the harm does not simply reverse when the prescription ends.
A person who experienced a serious depressive episode during treatment may carry that experience forward — in the form of ongoing mental health treatment, a changed relationship with their own body and emotions, or a lasting fear about hormonal medications that affects future care decisions.
Psychological consequences
A suicidal crisis, even one that did not result in an attempt, can be traumatic. Many people describe a period of significant psychological disruption — difficulty trusting their own mind, fear of relapse, and the burden of explaining what happened to family members who witnessed the change. Some require ongoing psychological support that they did not need before starting the medication.
Financial consequences
Mental health treatment costs money. Psychologist appointments, psychiatrist reviews, and medication for depression all carry a financial burden. Some people lose income during a period of incapacity. Others reduce their working hours or leave employment altogether during a serious episode. These costs accumulate over time and may be significant.
Hot flushes and night sweats
Reduced libido (in most cases)
Mild mood fluctuations
Sleep disturbance
Vaginal dryness
A clinical depressive episode triggered during treatment
Psychological trauma from a suicidal crisis
Bone density loss from prolonged use without monitoring
Disrupted relationships and employment during a serious episode
Ongoing mental health treatment costs
What compensation can cover in GnRH antagonist cases
NSW law allows a person who has suffered harm through substandard medical care to seek compensation. That compensation can cover several categories of loss — not just the immediate injury, but its downstream effects on your life.
Compensation in these cases can include pain and suffering, the cost of past and future psychological treatment, lost income during a period of incapacity, and the cost of ongoing care or support. In cases involving serious psychiatric harm, these amounts can be substantial.
| Level of harm | Typical compensation range |
|---|---|
| Moderate injury | $50,000–$150,000 |
| Serious injury | $150,000–$500,000 |
| Severe / life-changing injury | $500,000+ |
Each case is assessed on its own facts. These figures are general ranges only. Time limits apply to legal claims in NSW — generally three years from the date the person knew, or ought reasonably to have known, that they had suffered harm. Acting within that window matters.
Bringing it together — do the pieces fit?
Not every difficult experience with a GnRH antagonist medication points to a failure in care. But some do. The question is whether what happened to you matches a pattern of care that fell below what a reasonable clinician would have provided.
Understanding how a legal claim actually works in NSW can help you decide whether to take the next step. Reframe Legal — How Medical Negligence Claims Work in NSW explains the process in plain language.
You don’t need certainty to understand your position
Many people who experienced harm on a GnRH antagonist medication spend a long time wondering whether what happened was their fault — whether they were simply sensitive, or whether they should have pushed harder for help. That self-doubt is common. It does not mean nothing went wrong.
Legal clarity does not come from certainty about what happened. It comes from examining the facts — what the prescriber did, what they documented, what they said, and what a competent clinician in that position should have done. You do not need to have that answer before you start asking questions.
Informed consent is one of the most important legal concepts in this area. A patient who was not properly warned about a risk cannot be said to have consented to bearing that risk. Reframe Legal — Informed Consent and Medical Negligence explains how this principle applies in NSW.
If you want to understand whether your prescriber met their professional obligations, AHPRA — Australian Health Practitioner Regulation Agency oversees the registration and conduct of medical practitioners in Australia. AHPRA handles complaints about professional conduct separately from legal claims for compensation.
About the lawyer behind this article
Dr Rosemary Listing is a NSW medical negligence lawyer with a PhD focused on the legal and clinical dimensions of medical harm. Her academic and legal work examines how failures in the prescribing and monitoring of medications cause harm that patients often struggle to name or explain.
Rosemary has worked with clients whose experiences with hormonal suppression therapy — including GnRH antagonist medications — involved inadequate informed consent, absent monitoring, and prescription lapses without clinical follow-up. She understands that the harm in these cases often unfolds slowly, and that patients frequently blame themselves before they recognise that a system failed them.
Her view is that the most serious harm in GnRH antagonist cases rarely comes from the medication alone. It comes from the gap between what the prescriber knew about the risks and what the patient was told — and from the absence of any safety net when things started to go wrong.
Clients who approach Rosemary are not looking to punish a doctor. Most want to understand what happened, whether it should have happened, and what their options are. Her role is to assess the facts against the standard of care a competent clinician would have met.
Rosemary practises in New South Wales and works with clients across the state.
This article is general legal information only. It does not constitute legal advice. Each person’s circumstances are different. The law discussed applies to New South Wales, Australia. Time limits apply to legal claims. If you are experiencing a mental health crisis, please contact Lifeline on 13 11 14 or attend your nearest emergency department.