By Mike Kocsis | 10 minutes read | Last updated: June 3, 2025 Categories: Testosterone
Medically Reviewed by Dr. George Touliatos
If you are suffering from testosterone reduction or have symptoms of low testosterone, you may have come across testosterone Nebido injections as a possible treatment method for this condition.
Testosterone Nebido (having testosterone undecanoate as the active ingredient) is an injection that contains the most important hormone in the male body: testosterone.
Those who take Nebido injections are doing so with the goal of using the testosterone to raise the levels of testosterone in their body.
This article talks about everything you need to know about testosterone Nebido/ undecanoate, including its uses, side effects, dosage, cost, and more.
What is testosterone undecanoate/ testosterone Nebido?
Testosterone undecanoate is a synthetic form of a naturally occurring male hormone called endogenous testosterone.
It is a long-acting ester, which means that in it testosterone is attached to a fatty acid (undecanoic acid) that allows its ‘slow release’ and prolonged action in the body.
Testosterone undecanoate is prescribed to men with testosterone deficiency due to hypogonadism or any other health condition. It helps them boost their serum testosterone levels and curb low testosterone symptoms.
Nebido is a brand name for a formulation of testosterone undecanoate. It is popularly used in hormone replacement therapy (HRT) for men in Europe.
Testosterone Aveed is another well-known brand of testosterone undecanoate that is more commonly used in the United States.
Note: In this article, we will use testosterone Nebido and testosterone undecanoate interchangeably as they refer to the same substance.
How do testosterone Nebido injections work?
Testosterone Nebido is injected into your body, usually into a muscle (intramuscular injection).
Once injected, testosterone Nebido is gradually released into the bloodstream over a period of time. This provides an evenly distributed effect that increases the effectiveness of the injection.
Testosterone undecanoate is cleaved (or metabolised) primarily in the bloodstream, where enzymes break the ester bond and release the active form of testosterone.
Testosterone is then free to circulate in the bloodstream and exert its effects on various tissues, including muscles, brain, and reproductive organs.
Some of its effects are:
- Increase in muscle mass
- Improvement in bone mineral density
- Enhanced libido (sex drive)
- Improvement in mood and energy levels
- Deepening of the voice
- Body fat distribution regulation
- Cognitive function improvement
What is the use of testosterone undecanoate?
Nebido is most commonly used as a TRT treatment for men who are having a lack of testosterone on the NHS in the UK.
There are many causes of low testosterone, such as:
- Age-related testosterone decline
- Male hypogonadism
- Testicular damage or injury
- Pituitary or hypothalamic dysfunction
- Chronic diseases, such as diabetes or obesity
- Genetic conditions, such as Klinefelter syndrome
- Certain medications
- Poor lifestyle habits
There are many ways to know if you are experiencing low testosterone, as the symptoms are well-documented. Here are some of the possible symptoms of low testosterone:
- Impotence
- Infertility
- Low sex drive
- Fatigue
- Depression
- Bone density loss
- Muscle mass loss
If you are experiencing any combination of these symptoms, you may have low testosterone and need testosterone replacement therapy (TRT).
Testosterone undecanoate for bodybuilding
Testosterone undecanoate, commonly known as Nebido, is commonly used by athletes or bodybuilders because of its ability to increase muscle mass and strength.
They generally take its higher doses (despite having normal blood testosterone levels) to boost their performance.
However, know that testosterone is only approved to be used for testosterone deficiency.
Misusing testosterone undecanoate for bodybuilding purposes, in doses higher than those recommended for medical use, can lead to potential side effects.
Always use the substance responsibly under the guidance of a healthcare professional to avoid adverse health consequences.
What is the half-life of testosterone undecanoate?
The half-life of testosterone undecanoate is approximately 33.9 days (in castor oil).
This long half-life is one of the reasons why Nebido (testosterone undecanoate) is administered less frequently compared to other testosterone forms, such as testosterone enanthate or testosterone cypionate.
How long does testosterone undecanoate take to work?
Testosterone undecanoate or Nebido oily solution produces rewarding effects.
However, the time course of these effects varies from person to person, depending on factors like baseline testosterone levels, age, and overall health.
Generally, testosterone undecanoate’s full benefits are realised over a longer period of consistent use.
Clinical trials show that some effects, like improvement in mood, become prominent in a few weeks, while others, like improvement in bone density, may take several months to manifest fully.
How to inject testosterone Nebido or undecanoate?
To start the treatment, your doctor or medical professional will administer Nebido slowly into one of the muscles in the body.
The Nebido type of injection is strong and will last for a while, making it more convenient to use Nebido injections than some other types of TRT injections.
The delivery method makes Nebido injections an effective way to raise testosterone in the body.
The reason for this is the fact that injections are the most direct route to get testosterone into the bloodstream.
Testosterone Nebido also comes in undecanoate oral capsule form. They are used less frequently due to their lower bioavailability, as they must pass through the digestive system.
Where to inject testosterone undecanoate?
Testosterone undecanoate is usually injected into the ventrogluteal, deltoid, or another dense muscle area.
How often to take testosterone undecanoate?
In a Nebido injection, the injection site creates a natural reservoir of testosterone, which is gradually released over weeks.
This provides an evenly balanced treatment that maintains stable testosterone levels without the sharp peaks and drops associated with more frequent injections.
With properly administered Nebido treatments, you will only have to receive an injection every 10 to 14 weeks.
This timeframe and the wide period of time between two injections make it a highly desirable treatment.
How much testosterone undecanoate should I take?
Testosterone undecanoate dosage depends on multiple factors, like your testosterone levels, your treatment needs, etc.
1,000 mg (4 mL) of testosterone undecanoate is usually given every 10 to 14 weeks to increase and stabilise your testosterone levels.
If you are using oral testosterone undecanoate capsules, the typical dose is usually around 120 to 160 mg per day.
How long does testosterone undecanoate stay in your system?
As mentioned earlier, testosterone undecanoate injection has a 33.9-day half-life. This means, after this duration, half of the drug will be eliminated from your body.
And it will take the drug 5 to 6 half-lives to be completely removed from the body.
When not to use Nebido/ undecanoate
There are many medical conditions that might prevent someone from using Nebido injections.
Here are some of the characteristics that may make you a bad candidate for Nebido injections as a treatment for low testosterone:
- Allergies to testosterone or other ingredients that are included in Nebido injections
- Any cancer that is androgen-dependent or cancer that is present in the breast or prostate gland
- Have liver tumours or have had liver tumours in the past
Additionally, Nebido injections are not intended for use in women and they are not intended for use in children or adolescents.
There is no benefit in using Nebido injections for males under the age of 18.
All of these people who fit within these descriptions should not use Nebido injections as a treatment for any condition.
If it is decided by your doctor that you are a suitable candidate, you will still need to monitor your health over time and observe any side effects that might occur while you are using Nebido injections.
It is important that you stay in communication with your medical professionals and you notify them if you are having any TRT side effects.
If you have had any of the following before starting your Nebido injection treatments or you experience them after, contact your doctor to reevaluate your treatment plan and determine if TRT is still the right option for you:
- Epilepsy
- Heart problems
- Migraines
- Sleep apnea
- Cancer
- Hypertension
- Blood clotting
- Liver disease
- Kidney Disease
Starting Nebido treatment
Before you start Nebido injections, there are some steps to take with your medical team.
First, your doctor will conduct a testosterone blood test to evaluate your testosterone levels.
This biochemical test will help your medical team determine whether the treatment is having the desired effect.
In the beginning, your doctor may give you the second injection after only 6 weeks of treatment to frontload the effects and get you started with your Nebido injections.
From there on out, you can expect injections every 10 to 14 weeks. This is done to quickly reach the desired testosterone level so that you can enter the maintenance portion of the treatment.
Maintaining Nebido testosterone undecanoate levels
The next stage in the Nebido injection treatment is to achieve and maintain normal testosterone levels after the initial injections.
During this time, your doctor will continue to take tests and determine the amount of testosterone in the blood. They will determine if there is enough during this time and if adjustments need to be made in your TRT dosage or frequency.
Where & how to get testosterone Nebido in the UK?
Follow these simple steps if you want to buy testosterone in the UK:
- Speak to one of our consultants about your health symptoms.
- Undergo a full testosterone blood test to check for health issues.
- Upon successful diagnosis of low testosterone, we will offer you a variety of treatment options.
- Depending on your preference and what we think will work best for you, we may prescribe you testosterone Nebido.
- Testosterone Nebido prescriptions will be issued, and your health and TRT effects will be monitored on an ongoing basis.
What are the possible side effects of testosterone Nebido injections?
Here are some of the most common side effects that are associated with Nebido injections:
- High red blood cell count
- Weight gain
- Hot flashes
- Acne
- Enlarged prostate or prostatic disorders
- Irritation at the testosterone injection site
Here are some of the lesser-common side effects that you may experience during Nebido injection treatments:
- Allergic reactions
- Increased appetite
- Depression
- Migraines
- Fatigue
If you experience any of these symptoms and you are concerned about your health and comfort, you should contact your doctor immediately.
Testosterone cypionate vs enanthate vs undecanoate
Testosterone comes in different formulations for hypogonadal men. Here are the key differences between the three commonly used testosterone preparations:
| Feature | Testosterone cypionate | Testosterone enanthate | Testosterone undecanoate |
| Half-life | Around 8 days | Around 5 days | Around 33 days |
| Injection frequency | Every 7 to 10 days | Every 7 to 10 days | Every 10 to 14 weeks |
| Form | Injectable (oil-based) | Injectable (oil-based) | Injectable (oil-based), oral capsules |
| Use | Commonly used for testosterone treatment, TRT | Commonly used for testosterone therapy, TRT | Commonly used for TRT |
Testosterone Nebido / undecanoate dosage
Testosterone Nebido comes in the form of an injectable solution containing testosterone undecanoate. The usual starting and maintenance dose for Testosterone Nebido is 1,000 mg (4 mL) every few weeks.
However, dosage can vary from patient to patient. Ask your doctor dosage-related questions before getting started with TRT.
Testosterone Nebido costs in the UK
TRT treatment packages for testosterone Nebido cost between £70 and £113 per month, depending on the treatment options you go for. If you want to learn how to get testosterone Nebido or what the cost of TRT is in the UK, then contact us.
Conclusion
Nebido injections have long been one of the most successful and commonly used testosterone treatment programs for men who are experiencing low testosterone levels.
TRT in the UK is an effective approach to boosting serum testosterone levels and improving overall quality of life.
Speak to one of our consultants for free at Balance My Hormones to discuss your testosterone issues and potential treatment options.
References
Goldstein, I., Chidambaram, N., Dobs, A., King, S., Miner, M., Ramasamy, R., Yafi, F.A. and Khera, M., 2025. Newer formulations of oral testosterone undecanoate: development and liver side effects. Sexual medicine reviews, 13(1), pp.33-40.
Campbell, K., Muthigi, A., Ghomeshi, A., Schuppe, K., Sandler, M.D. and Ramasamy, R., 2023. Safety aspects and rational use of testosterone undecanoate in the treatment of testosterone deficiency: clinical insights. Drug, healthcare and patient safety, pp.73-84.
Abildgaard, J., Petersen, J.H., Bang, A.K., Aksglaede, L., Christiansen, P., Juul, A. and Jørgensen, N., 2022. Long‐term testosterone undecanoate treatment in the elderly testosterone deficient male: an observational cohort study. Andrology, 10(2), pp.322-332.
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About the Author: Mike Kocsis
Mike Kocsis has an MBA with a focus on healthcare administration and is an entrepreneur and medical case manager for Balance My Hormones which offers medical services in the UK and Europe. Mike has over 20 years of experience in the healthcare sector, much of that working with people who have hormone imbalances. Mike has appeared on podcasts and radio and is an expert speaker on the subject of hormone imbalance. He specialises in Testosterone Replacement Therapy and Hormone Replacement Therapy (HRT) and has helped thousands of people suffering from hormone imbalances recover and regain control of their lives. You can follow him on LinkedIn and on the Balance My Hormones YouTube Channel.
Last update: June 3rd, 2025
