Androgen Deprivation Therapy (ADT) Side Effects: What to Expect and How to Manage Them

Androgen deprivation therapy (ADT) is one of the most effective tools in prostate cancer treatment — dropping testosterone to castrate levels starves the cancer of the hormone it depends on to grow. Most of what men are told before starting ADT focuses on that decision: is it the right treatment, and for how long. What gets far less airtime is what daily life actually looks like once testosterone is near zero for months or years.

That gap matters, because ADT's side effects aren't rare or minor — they touch bone density, cardiovascular risk, muscle mass, and quality of life in ways that are largely predictable and, in several cases, preventable if you know what to watch for and act early rather than after a fracture or a cardiac event forces the issue. This guide walks through the major side effect categories in the order most men notice them, with what the actual evidence says about managing each one.

How ADT Lowers Testosterone

ADT achieves castrate testosterone levels (traditionally defined as below 50 ng/dL, though modern agents often push well below 20 ng/dL) through one of several mechanisms: GnRH/LHRH agonists (leuprolide, goserelin) that paradoxically shut down pituitary signaling after an initial testosterone surge; GnRH antagonists (degarelix, or the oral option relugolix) that suppress testosterone directly without that surge; anti-androgens that block testosterone's effect at the receptor rather than lowering the hormone itself; and surgical orchiectomy, which is permanent. Which mechanism you're on matters for side effects, not just for cancer control — as the cardiovascular section below explains.

Hot Flashes: The Most Common Side Effect

Hot flashes affect the large majority of men on ADT, often starting within the first few months and, for some, persisting for years. The mechanism mirrors menopausal hot flashes — the hypothalamus's temperature-regulation center becomes destabilized when sex hormone levels drop sharply.

A 2019 systematic review of 15 randomized and quasi-experimental trials on managing ADT-associated hot flashes found real but limited evidence: hormonal agents like megestrol acetate and cyproterone reduced hot flash frequency but came with their own side effect trade-offs, while acupuncture showed some benefit without added risk. The review's honest conclusion was that no single intervention has strong, well-powered evidence behind it — which is a useful thing to know before assuming any one option is a guaranteed fix [5]. Non-hormonal medications such as venlafaxine or gabapentin are commonly used off-label and are worth discussing with your oncologist if hot flashes are significantly disrupting sleep or daily function.

Bone Loss and Fracture Risk

• •Testosterone (via its conversion to estrogen) is a key driver of bone maintenance in men — removing it accelerates bone turnover and bone mineral density (BMD) loss well beyond normal age-related decline
• •This isn't a cosmetic concern: accelerated BMD loss translates directly into a higher risk of fragility fractures, particularly of the hip and spine, the longer ADT continues
• •A baseline DEXA (bone density) scan before or shortly after starting ADT gives you and your care team an actual number to track against, rather than guessing
• •Weight-bearing exercise, adequate calcium and vitamin D intake, and avoiding smoking and excess alcohol all support bone health during treatment

For men at higher fracture risk, bone-protective medication is a genuine, evidence-backed option rather than a precaution taken "just in case." A landmark randomized, double-blind trial of denosumab in men on ADT for non-metastatic prostate cancer found lumbar spine BMD increased 5.6% at 24 months in the denosumab group versus a 1.0% loss with placebo, with new vertebral fractures cut from 3.9% to 1.5% at 36 months [2]. Bisphosphonates (zoledronic acid, alendronate) are the other main class used for the same purpose.

Cardiovascular Risk

ADT is associated with an increased risk of major cardiovascular events, and — importantly — this risk isn't identical across every type of ADT. A 2020 phase 3 trial comparing the oral GnRH antagonist relugolix against the standard GnRH agonist leuprolide found major adverse cardiovascular events in 2.9% of men on relugolix versus 6.2% on leuprolide over 48 weeks — a 54% relative risk reduction favoring the antagonist [3]. This doesn't mean agonists are unsafe for everyone, but it does mean the choice of ADT agent is a legitimate conversation to have with your oncologist, particularly if you already have cardiovascular disease or significant risk factors for it.

Practical steps that apply regardless of which ADT agent you're on: get a baseline cardiovascular risk assessment before starting treatment if you haven't had one recently, keep blood pressure, cholesterol, and blood sugar under active management rather than deferring them, and flag any new chest pain, shortness of breath, or unusual fatigue to your care team promptly rather than assuming it's just "part of treatment."

Muscle Loss and Fatigue

Testosterone directly supports muscle protein synthesis, so its near-total removal on ADT predictably reduces lean muscle mass and strength while increasing fat mass — a pattern that compounds fatigue and reduces quality of life if left unaddressed.

The encouraging finding here is that this process isn't purely one-directional. A controlled trial of 12 weeks of structured resistance training in older men on ADT found significant increases in total body muscle mass (2.7%), thigh muscle volume (6.4%), strength (28%), and functional performance (20%), alongside a 38% reduction in perceived fatigue — despite testosterone remaining suppressed throughout [4]. In plain terms: you don't need testosterone to rebuild muscle on ADT, but you do need a structured resistance training program, not just general activity, to get there.

• •Resistance training 2-3 times per week is the single best-evidenced countermeasure for ADT-related muscle and strength loss
• •Adequate protein intake supports the muscle-building stimulus from training
• •A supervised program (physical therapist or exercise physiologist familiar with cancer patients) is worth seeking out if you're deconditioned or have other health complications

Sexual Function, Mood, and Cognition

Near-zero testosterone essentially eliminates libido and erectile function for most men on ADT — this is an expected, mechanism-driven effect rather than a separate complication, and it's distinct from the erectile dysfunction that can follow prostatectomy or radiation directly (see the related articles below for those specific recovery paths). ADT is also associated with mood changes and measurable, if usually modest, effects on cognition and processing speed in the research literature [1]. These effects are real but frequently under-discussed — raising them with your care team, and with your partner, tends to make them easier to manage than treating them as an unspoken side effect.