Side effects of brachytherapy

All treatments for prostate cancer carry a risk of side effects.

Radiation therapy in general is often associated with side effects. These side effects are well known and most side effects do not depend on the type of radiation therapy. However, brachytherapy is associated with sparing surrounding healthy tissue from unnecessary radiation with the potential for fewer side effects than alternatives such as external beam radiotherapy.

People respond to treatments in different ways. The type of side effects that may be experienced depends on a number of factors such as the stage of the prostate cancer and whether there are any compounding health problems. The majority of brachytherapy patients receive a multimodality treatment with other treatments such as surgery, EBRT and androgen deprivation therapy (ADT). This makes it very difficult to distinguish between side effects from brachytherapy, side effects caused by other treatments and disease related symptoms and complications.

Short-term (acute) side effects

Immediately after the brachytherapy procedure, you may experience some of the following:1

  • Soreness or localized bruising around the perineum (the area between the scrotum and anus where the needles are inserted to deliver the brachytherapy).
  • Blood in urine and/or semen.
  • Discomfort when passing urine (may include needing to pass urine urgently or frequently).
  • These short-term side effects are typically mild in nature and usually resolve soon after treatment.

Long-term side effects

Possible long-term side effects of brachytherapy include:2

  • Urinary discomfort (may include needing to pass urine urgently or frequently, or finding it difficult to pass urine).
  • Bowel discomfort.
  • Erectile dysfunction.

People respond to treatments in different ways and you may or may not experience some of these side effects. Importantly, the long-term risks are generally lower with brachytherapy compared to other treatment options for prostate cancer.3

Furthermore, even if you are affected by some of these side effects, many patients find that their urinary, bowel and sexual function returns to normal after 6-12 months.

Safety of radiation

A common question about brachytherapy is whether the procedure causes any radiation risks to family and friends.

If high dose rate (HDR) brachytherapy is used, the radiation sources are only temporarily placed in the body and are removed after each treatment. Hence, there is no radiation risk to family or friends.

If low dose rate (LDR) brachytherapy (seed therapy) is used, only the seeds give out radiation and these will not make you radioactive. The radiation levels given out by the seeds are low, however, your healthcare professional may advise you to avoid close contact with small children and pregnant women after the brachytherapy procedure.

The Precise Answer for Tackling Prostate Cancer

Download the prostate cancer patient guide (pdf)


  1. Zamboglou N et al. Int J Radiat Oncol Biol Phys. 2013;85(3):672-8. Available at: Accessed June 2021
  2. Hoskin P at al. Radiother Oncol 2021;154:214-19. Available at: Accessed June 2021
  3. Hoffman K et al. JAMA 2020;323(2):149-163. Available at: Accessed June 2021