There is no fixed maximum duration for Eligard. The FDA label does not set an endpoint, and long-term data shows the drug maintains its testosterone-suppressing effect for at least seven years of continuous use. How long you actually stay on it depends on your cancer’s stage, whether you’re also receiving radiation, and how your body tolerates the side effects over time.
Treatment Duration Depends on Cancer Stage
Eligard (leuprolide acetate) is a form of androgen deprivation therapy, or ADT, that lowers testosterone to slow prostate cancer growth. It comes in formulations that last one, three, four, or six months between injections. But the total length of treatment varies widely based on your clinical situation.
For men receiving radiation therapy after surgery, treatment courses typically fall into two categories: short-course (4 to 6 months) or long-course (24 months). A large randomized trial called RADICALS-HD compared these two durations in men getting post-surgical radiation and found that 24 months of ADT improved outcomes over 6 months for certain higher-risk patients. An earlier trial, RTOG 9601, also showed that two years of hormonal therapy alongside post-operative radiation improved long-term survival.
For advanced prostate cancer, which is Eligard’s FDA-approved indication, treatment often continues indefinitely. The goal in this setting is palliative: keeping testosterone suppressed to control the disease for as long as possible. Many men with advanced cancer remain on Eligard for years without a predetermined stopping point.
When the Cancer Stops Responding
One practical limit on Eligard’s usefulness is the development of castration-resistant prostate cancer. This happens when the cancer learns to grow even with testosterone at very low levels. In clinical data, the average time to castration resistance was roughly 2.5 to 2.7 years (about 976 to 986 days), though this varies significantly between individuals. Some men respond for much longer, while others develop resistance sooner.
Once cancer becomes castration-resistant, your oncologist will typically add or switch to other treatments. Even then, Eligard is often continued in the background because allowing testosterone to rise could accelerate cancer growth further.
Side Effects Accumulate Over Time
The risk of side effects increases the longer you stay on Eligard. Because testosterone affects far more than just the prostate, suppressing it for months or years can cause bone density loss, fractures, muscle loss, weight gain, changes in cholesterol and blood sugar, fatigue, and insulin resistance. These aren’t just temporary inconveniences. Some changes, particularly bone loss, can persist even after stopping the drug.
For men on long-term treatment, doctors often prescribe bone-protecting medications like bisphosphonates or denosumab to counteract the accelerating loss of bone density. Regular exercise also meaningfully reduces several of these side effects, including bone loss, muscle wasting, weight gain, and fatigue. Your response to Eligard should be monitored periodically with blood tests checking both testosterone and PSA levels to confirm the drug is still working.
Intermittent Therapy as an Alternative
Because of the cumulative side effect burden, some men are candidates for intermittent ADT rather than continuous treatment. In this approach, you take Eligard until your PSA drops to a low level, then stop until it rises again. This gives your body a break from testosterone suppression, which can improve quality of life during the off periods. Research comparing intermittent and continuous ADT has found no significant difference in the time to castration resistance between the two approaches, suggesting the on-and-off strategy doesn’t make the cancer progress faster.
Not everyone qualifies for intermittent therapy. It’s generally considered for men with a good initial PSA response and lower-volume disease. Your oncologist will weigh the tradeoff between side effect relief and the certainty of continuous suppression.
What Happens When You Stop
Testosterone recovery after stopping Eligard is gradual and not guaranteed. Data from Memorial Sloan Kettering found that at 6 to 12 months after stopping ADT, average testosterone levels were still quite low, around 216 ng/dL. By 12 to 18 months, levels climbed to about 275 ng/dL. At 18 to 24 months, they reached approximately 292 ng/dL, and beyond two years, they averaged 321 ng/dL.
At the two-year mark, about 76 percent of men had recovered to a normal testosterone level (above 300 ng/dL), but only 51 percent returned to their original baseline. Eight percent remained at castrate levels, meaning their bodies never fully recovered testosterone production. Two factors made recovery less likely: having been on ADT for longer than six months, and having lower testosterone before starting treatment. Older age also worked against recovery.
This recovery timeline matters because the side effects of low testosterone, including fatigue, sexual dysfunction, and bone fragility, persist until levels normalize. Men who stop Eligard after years of use should expect a long, sometimes incomplete, recovery period.