Why are GnRH agonist drugs used in androgen deprivation therapy?

GnRH agonists act on the hormone-control system. At the start, they can briefly stimulate the pituitary gland; with continued treatment, that signalling becomes suppressed. The testes then receive less stimulation to make testosterone, so the body's androgen level falls.

Lowering testosterone can slow the growth of prostate cancer cells that depend on androgen signals. A clinician may use the medicine alone or combine it with other treatment, depending on the cancer and treatment plan. An early temporary hormone rise can worsen symptoms in some people, so the team may discuss additional medicine around the first dose.

Keep injection or implant appointments and do not stop treatment without speaking with the prescribing team. Report new bone pain, difficulty passing urine, hot flushes, mood changes, sexual symptoms, or marked tiredness so these can be managed. Tell the team about heart disease, diabetes, bone problems, and all medicines because hormone changes can affect wider health.

Seek urgent help for inability to pass urine, severe new back pain with leg weakness or numbness, chest pain, fainting, or sudden breathlessness. Contact the oncology team quickly for rapidly worsening cancer symptoms or severe mood changes. Early review can identify pressure on nerves, urinary blockage, or treatment effects that need attention.

Ask how the first dose will be managed, how testosterone and prostate-specific antigen will be monitored, and which side effects deserve a same-day call. Discuss exercise, bone health, heart health, and whether another hormone-blocking medicine is part of your plan.