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Generic Name: Testosterone undecanoate
Product Name: Reandron


Reandron is a medication used to treat men with hypogonadism, a condition characterised by abnormally low levels of testosterone in the blood.


The active ingredient in Reandron, testosterone undecanoate, is converted to testosterone once it is injected into the body. This increases blood testosterone levels within a day of the injection. The testosterone in a Reandron injection performs the same functions as the testosterone produced naturally by the body, such as developing the male genitals and secondary sex characteristics (e.g. hair growth, body fat distribution).

Dose advice

Dose information

Reandron is an oily substance that must be injected intramuscularly by a health professional. It is injected deep into the gluteal muscle (buttocks). The recommended dose is one injection, containing 1,000 mg of the active ingredient testosterone undecanoate, every 10–14 weeks.

The prescribing doctor will decide exactly how often the injection should be administered depending on your response to the treatment. To determine the response to treatment, the doctor will usually assess clinical symptoms of testosterone deficiency (e.g. lack of facial hair, small testicles) and measure your blood testosterone levels when the next Reandron injection is due.

If your blood testosterone is lower than the normal range of testosterone levels, you will require more frequent testosterone injections (e.g. every 10 weeks). If you do not achieve high enough blood testosterone levels, you may receive the second testosterone injection after a minimum of 6 weeks (instead of the usual 10 week minimum). If your testosterone levels increase excessively, you will require less frequent testosterone injections (e.g. 14 weekly).

Always take Reandron as prescribed by the doctor. It is important never to miss a scheduled injection appointment, even if you are not experiencing symptoms of testosterone deficiency at the time the injection is due. Reandron is not a cure for testosterone deficiency. Ongoing treatment is required to maintain normal testosterone levels.


Reandron should not be used by women or males aged < 18 years. It should also not be used by adult men with:


Doctors will only prescribe Reandron after they have made a definitive diagnosis of testosterone deficiency. This means the diagnosis is based on both clinical symptoms (e.g. underdevelopment of secondary sex characteristics) and biochemical evidence (i.e. blood testosterone levels). Reandron is not a medicine that can be used to promote muscle development or improve physical fitness, and doctors will not prescribe it for these purposes. Using Reandron to improve physical fitness carries serious health risks.

Before prescribing Reandron, the doctor will investigate any co-existing medical conditions that may cause testosterone deficiency (e.g. diabetes, obesity). If your testosterone deficiency is caused by another medical condition, you probably should not receive testosterone injections, but rather should receive treatment for the underlying condition.

Your blood testosterone levels will be regularly measured while on Reandron treatment. This allows the doctor to assess the effectiveness of the treatment and determine the most appropriate dosing schedule.

Reandron may stimulate the growth of prostate and breast cancers, and doctors will therefore ascertain that you do not have these cancers before starting treatment. This usually involves a digital rectal examination and a PSA test. While you are using Reandron, you will also be monitored on an annual basis for the development of these cancers (unless you have risk factors for the cancers such as old age, in which case you may need to be examined every 6 months). Other blood tests may also be conducted to ensure your blood concentrations remain normal while on Reandron.

Special consideration needs to be taken before using Reandron with certain conditions. Tell your doctor if you are or have:

  • Bleeding or coagulation disorders: You should receive another, non-injectable form of testosterone, as the injection may worsen the bleeding disorder;
  • Predisposition to oedema;
  • Professional athlete: Reandron treatment may lead to positive doping test results;
  • Develop symptoms such as nervousness, irritability, weight gain or prolonged or frequent erections while on Reandron: These symptoms indicate that the testosterone dose is too high and may require adjustment;
  • Upper abdominal pain, liver enlargement or symptoms of bleeding in the abdomen while on Reandron: These may indicate liver tumours;
  • History of:
    • High blood pressure;
    • Abnormal kidney function;
    • Migraine;
    • Epilepsy;
    • Cardiac insufficiency;
    • Sleep apnoea.
    • Anaphylactic (allergic) reaction following injection of a medicine or vaccine: Anaphylactic reaction is a rare but dangerous side effect of injectable medication which may produce life-threatening symptoms, including swelling of the face and lips and difficulty breathing;
  • Taking any other medications: These medicines may affect the way Reandron works, or Reandron may affect the way your other medicines work. Medicines known to interact with Reandron include:
    • Hypoglycaemic agents, such as insulin used to treat diabetes;
    • Medications that increase microsomal enzymes (e.g. barbituates);
    • Oral anticoagulants (blood-thinning medications);
    • Cyclosporin (a medicine that suppresses the immune system);
    • Oxyphenbutazone (an anti-inflammatory medication used to treat pain);
    • Substances that effect liver function, including herbal preparations (e.g. eucalyptus, comfrey, valerian).

Use in pregnancy

Reandron is a Pregnancy Category D medication. It should not be used by women. Its use during pregnancy is likely to cause over-development of male sex characteristics in female foetuses.

Use in breastfeeding

Reandron should not be used by women and should not be used during breastfeeding.

Use in children

The effects of Reandron on children and adolescents less than 18 years old have not been determined and the use of this medication is not recommended in these groups.

Use in older people

The risk of developing prostate cancer is increased in older individuals treated with androgens such as Reandron. The dose of Reandron given to older people is not any different from other age groups.


Reandron is a Schedule 4 medication.1

Common side effects

All medicines have side effects. Most commonly the side effects are minor; however, some can be more serious. Usually the benefits of taking a medication outweigh the associated side effects. Your doctor would have considered these side effects before starting you on Reandron.

Common side effects are those that occur in more than 1% of people given Reandron. These include:

  • Polycythaemia, a condition characterised by excessive red blood cells which can be diagnosed with a blood test;
  • Weight gain;
  • Acne;
  • Abnormal prostate examination and/or test;
  • Hot flushes;
  • Injection site pain or other reactions at the injection site including bruising and itching;
  • Reversible impairment of sperm production.

Uncommon side effects

Uncommon side effects are those that occur in 0.1–1% of Reandron users. People do not necessarily experience any of these side effects, so do not become alarmed after reading this list. However some of the side effects of Reandron are serious and require prompt medical attention.

Tell your doctor if you experience any of the following symptoms whilst using Reandron:

  • Abnormal blood test results;
  • Diarrhoea;
  • Nausea;
  • Increased appetite;
  • Abnormal blood chemistry test results;
  • Increased blood cholesterol;
  • Pain in extremities (arms and legs);
  • Muscle spasms;
  • Muscle strain;
  • Muscle pain;
  • Joint pain;
  • Musculoskeletal stiffness;
  • Tremor;
  • Emotional disorder;
  • Insomnia;
  • Restlessness;
  • Inflammation of the respiratory system;
  • Snoring;
  • Feeling uneasy, unwell, depressed or anxious;
  • Abnormal liver function test results;
  • Hair loss;
  • Dry skin;
  • Itch;
  • Abnormal urine production and frequency of voiding;
  • Prostate abnormalities;
  • Testicular pain;
  • Changes to libido;
  • Hardness in the breast;
  • Changes in sex hormone concentrations in the blood;
  • Abnormally large breasts;
  • Cardiovascular disorder;
  • Increased blood pressure.

Some uncommon side effects can require urgent medical attention. These include:

Some uncommon side effects can be very serious. If you experience any of the following, you should tell your doctor immediately or go to the nearest Accident and Emergency department. These include:

(occurrence 0.01–0.1% of users) and very rare (occurrence ≤ 0.01% of users) side effects of Reandron use include:

  • Blockage of a blood vessel in the lungs;
  • Nervousness;
  • Hostility;
  • Sleep apnoea (particularly in overweight individuals or those with existing respiratory problems);
  • Skin reactions, including seborrhoea;
  • Increased frequency of erections;
  • Water retention;
  • Oedema;
  • Respiratory infections and disorders;
  • Joint disorders;
  • Inflammation of the nasal passages.

Some rare and very rare side effects can be very serious. If you experience any of the following, you should tell your doctor immediately or go to the nearest Accident and Emergency department. These include:

  • Jaundice (yellowing of the skin);
  • Persistent, unwanted and painful erection.

Severe abdominal pain has been observed with use of hormones such as Reandron, but there is no information on how commonly it occurs in Reandron use.  This symptom can indicate the presence of a liver cancer, and you should immediately inform your doctor if you have severe abdominal pain.

There are also other side effects which may occur whilst taking Reandron. If you experience any of the listed side effects, or any other symptoms that appear abnormal or unusual, please tell your doctor.


  1. Product Information: Reandron. Pymble, NSW: Bayer Australia Limited; 28 April 2011.
  2. Consumer Medicine Information: Reandron. Pymble, NSW: Bayer Australia Limited; February 2011.


For further information talk to your doctor.


Posted On: 4 December, 2007
Modified On: 23 May, 2012
Reviewed On: 8 June, 2011

Created by: myVMC