The most common injection given for prostate cancer is a hormone therapy shot that lowers testosterone, since testosterone fuels prostate cancer growth. These injections fall under a category called androgen deprivation therapy (ADT), and they are typically the first treatment most people with prostate cancer receive. Depending on the stage of cancer, other types of injections, including chemotherapy, immunotherapy, and radioactive drugs, may also be used.
Hormone Therapy Injections: The First-Line Treatment
Prostate cancer cells rely on testosterone to grow. Hormone therapy injections work by cutting off that supply, dropping testosterone to extremely low levels. There are two main types, and they work in slightly different ways.
The first and most widely prescribed type is called an LHRH agonist (sometimes called a GnRH agonist). These drugs trick the pituitary gland into stopping its signal to the testicles to produce testosterone. The most common options include leuprolide (sold as Lupron Depot, Eligard, and Camcevi), goserelin (Zoladex), and triptorelin (Trelstar). These are given as shots under the skin or into muscle, depending on the specific formulation. Subcutaneous injections use shorter needles and offer more flexibility in injection sites, while intramuscular shots go deeper into the muscle tissue.
The second type is an LHRH antagonist. Degarelix (Firmagon) is the injectable version. Instead of overstimulating the pituitary gland, it directly blocks the hormone signal, causing an immediate drop in testosterone. This distinction matters because LHRH agonists cause a temporary spike in testosterone during the first few weeks of treatment, known as a “testosterone flare.” That flare can briefly worsen symptoms, especially bone pain in men with advanced cancer. To prevent this, doctors sometimes prescribe a short course of anti-androgen pills before starting the agonist injection. LHRH antagonists skip this problem entirely. There is also a pill-form antagonist called relugolix (Orgovyx), which isn’t an injection but serves the same purpose.
How Often You Get the Shots
Hormone therapy injections aren’t daily or weekly. They come in extended-release formulations designed to last one month, three months, four months, or even six months per dose. Your oncologist will choose a schedule based on your specific treatment plan and how your body responds. Some men stay on these injections for a defined period, while others with advanced cancer remain on them indefinitely, sometimes adding other treatments on top.
The injection itself is quick, usually done in a doctor’s office or clinic. Subcutaneous shots typically go into the abdomen, while intramuscular shots go into the buttock or thigh. Injection-site reactions like redness or soreness are more common with subcutaneous formulations, but most people tolerate both routes well.
Side Effects of Testosterone-Lowering Injections
Because these injections essentially eliminate testosterone from the body, side effects reflect what happens when that hormone is absent. Hot flashes are one of the most common complaints and can range from mild warmth to drenching sweats. Many men also experience fatigue, reduced sex drive, and difficulty getting erections.
Over time, the effects go deeper. Bone density decreases, raising the risk of fractures. Muscle mass drops while body fat increases, particularly around the midsection. Some men develop insulin resistance and higher cholesterol, which increases cardiovascular risk. Mood changes, including depression and difficulty concentrating, are also reported. These side effects tend to accumulate the longer someone stays on treatment, which is one reason doctors weigh the timing and duration of hormone therapy carefully.
Chemotherapy Injections for Advanced Cancer
When prostate cancer stops responding to hormone therapy, a stage called castration-resistant prostate cancer, injectable chemotherapy becomes an option. Docetaxel is typically the first chemotherapy drug used. It’s given as an intravenous infusion, usually every three weeks. If the cancer progresses after docetaxel, cabazitaxel (Jevtana) is a second-line option, also given intravenously every three weeks as a one-hour infusion.
In some cases, docetaxel is now used earlier in treatment, combined with hormone therapy right from the start for men diagnosed with widespread metastatic disease. This approach, called treatment intensification, has become more common as evidence shows it can extend survival compared to hormone therapy alone.
Radioactive Injections for Bone Metastases
For men whose prostate cancer has spread to the bones, two injectable radioactive drugs can deliver targeted radiation directly to tumor sites. Radium-223 (Xofigo) was the first to gain FDA approval in 2013. It mimics calcium in the body, so it naturally concentrates in areas of active bone growth, which is exactly where bone metastases tend to be. It’s given intravenously every four weeks for six cycles and is specifically approved for men with symptomatic bone metastases who don’t have cancer spread to other organs.
A newer option, lutetium-177 (Pluvicto), was approved in 2022 and works differently. Rather than targeting bone, it locks onto a protein called PSMA that sits on the surface of most prostate cancer cells. Before receiving it, you need a special PET scan to confirm your cancer produces enough PSMA for the drug to find its targets. Pluvicto is reserved for men who have already been through both hormone-blocking drugs and chemotherapy. In the major clinical trial that led to its approval, roughly half of patients experienced significant side effects, with anemia being the most common serious one.
Immunotherapy: A Different Kind of Injection
Sipuleucel-T (Provenge) is a unique treatment that uses your own immune cells to fight prostate cancer. The process starts with a blood draw through a procedure called leukapheresis, which filters out specific immune cells. Those cells are shipped to a manufacturing facility, where they’re exposed to a protein found on prostate cancer cells. This “trains” the immune cells to recognize and attack the cancer. The activated cells are then shipped back and infused into your bloodstream. The entire cycle, from blood draw to infusion, takes about four days, and the full treatment involves three infusions spaced two weeks apart.
Provenge is used for advanced prostate cancer that no longer responds to hormone therapy but is causing few or no symptoms. It’s not a dramatic tumor-shrinking treatment, but it has been shown to extend survival. The infrastructure required is significant, as only specialized centers can offer it because the cells must be carefully transported, kept sterile, and infused before they expire.
How Doctors Choose Which Injection You Get
The type of injection depends almost entirely on the stage of your cancer and how it has responded to previous treatments. For localized or locally advanced prostate cancer, hormone therapy injections are the standard, often paired with radiation. For metastatic cancer that still responds to testosterone suppression, hormone injections continue but may be combined with chemotherapy or newer oral drugs. Once the cancer becomes resistant to hormone therapy, the toolkit expands to include chemotherapy infusions, radioactive drugs, and immunotherapy, chosen based on where the cancer has spread, what treatments you’ve already had, your symptoms, and your overall health.