Nebido: Uses, Mechanism of Action, Administration, Warnings, Side Effects and Interactions

The injection of this drug contains the active ingredient testosterone undecanoate, which is a component of the natural hormone testosterone.

For what do you use it?

Nebido injection is a testosterone replacement therapy in men with low natural testosterone production ( hypogonadism ).

Nebido is an ester-based testosterone injection that can be used by bodybuilders, weightlifters, and anyone else who wants to gain muscle and increase their overall strength .

Testosterone is a hormone that helps build and maintain muscle mass. For bodybuilders, powerlifters and the like, it is important to develop their muscle mass to increase their strength and achieve the results they seek.

Mechanism of action

Nebido injection contains the active ingredient testosterone undecanoate , which is a component of the natural hormone testosterone. Testosterone is known as an androgen.

It is produced by the testicles and is the main hormone essential for the normal growth and development of male sex organs and male sexual characteristics.

The natural production of testosterone is controlled by another set of hormones called gonadotropins, which are released from the pituitary gland in the brain.

During adult life, testosterone is essential for sperm production , maintenance of sexual drive, erotic potency, and the functioning of the prostate and other reproductive structures.

It also has functions in the skin, muscles, skeleton, kidney, liver, bone marrow, and central nervous system.

Low testosterone levels can cause:

  • Decreased sexual desire
  • Impotence.
  • Infertility due to decreased sperm production.
  • Decreased mental and physical activity.
  • Fatigue.
  • Weakening of the bones (osteoporosis).

Testosterone is given as replacement therapy when natural testosterone levels drop too low, causing problems like the ones above.

Natural testosterone levels slowly decline with age and decline rapidly after surgical removal of the testicles (for example, in the treatment of testicular cancer).

Hypogonadism or eunucoidism is caused by testicular disease, or by decreased gonadotropin production by the pituitary gland, as a result of pituitary disease. Testosterone replacement allows natural testosterone levels to return to normal, thus alleviating deficiency symptoms.


The injection of nebide is called a depot injection. It is injected slowly into the muscle of the buttock where it forms a reservoir of medicine. Testosterone is released gradually all the time from the reservoir into the bloodstream.

The injection is usually given once every 10 to 14 weeks, although the frequency depends on individual testosterone levels.

After the first injection, you may be asked to re-inject after just weeks, so that the correct level of testosterone is reached quickly.


You will need to do blood tests to measure your blood testosterone level before you start using it with this medicine.


Symptoms of weight gain, irritability, or nervousness will be evident after starting treatment with this drug.

There are also regular blood tests to check your red blood cell levels, liver function, and prostate specific antigen (PSA).

Testosterone can increase prostate cancer growth and benign prostate enlargement. Your doctor has several tests to make sure you do not have prostate cancer before starting treatment with this medicine.

Your doctor should perform a digital rectal exam to check your prostate at least once a year while you are receiving testosterone replacement (more often if you are an adult or have risk factors for prostate cancer).

Use with caution in:

  • Elderly people.
  • People with a history of kidney or liver disease.
  • People with a history of heart disease, for example heart attack or heart failure.
  • People with a history of high blood pressure (hypertension).
  • People with a history of migraines.
  • People with sleep apnea.
  • People with cancer that has spread from its original site to the bones (skeletal metastases).
  • People with a history of primary liver cancer.
  • People with a kidney disorder called nephrosis or nephrotic syndrome. People with a high level of calcium in the blood ( hypercalcaemia ).

Nebido injection is not recommended for children and adolescents under 18 years of age. This medicine should not be used if you are allergic to one of its ingredients.

Inform your doctor or pharmacist if you have already experienced such an allergy. If you experience an allergic reaction, stop using this medicine and tell your doctor or pharmacist immediately.


Nebido injection has active and inactive ingredients. It has an active ingredient called Testosterone Undecanoate. A nebido injection is made up of a 4 ml solution containing 1000 mg of the active ingredient, testosterone undecanoate.

Testosterone, either produced naturally by the body or introduced synthetically into the body, can help build a large amount of muscle. Inactive ingredients in nebido include benzyl benzoate and castor oil.

Sports use

Nebido injection can be used as long as needed. There is no time limit for its use. This is an advantage that nebido has over many other steroids.

Some steroids require discontinued use after a certain amount of time; this is not the case with nebido.

For bodybuilders and powerlifters, this is a huge positive, and is part of the reason why it is so widely used.

There are several benefits of using nebide that other steroids do not have. These benefits include, among others, the following:

  • With a half-life of approximately 3 months, nebido has one of the longest half-lives of any testosterone steroid on the market.
  • It is the same testosterone that the body naturally produces.
  • Build muscle and increase strength.
  • Burns fat.
  • Reduce fatigue.
  • Increase stamina.
  • Improve performance.
  • Improves muscle definition.
  • Accelerate recovery time.
  • Injections are less frequent than many other steroids.
  • It does not restrict activities such as swimming.
  • Alleviate the pain.

Side effects

Even though your body certainly needs testosterone, it is important to note that whenever you introduce an exogenous substance into your body, there will always be side effects.

These are effects to be aware of, and if you are aware of them, they won’t be as frustrating for you to experience or suffer should they happen.

This is very important to understand compared to other types of this hormone, because all too often, they can be very difficult to pin down. But with a novice understanding, you must be in good shape to progress and advance with this substance.

These side effects are possible, but they don’t always happen. Some of the side effects can be rare but serious. See your doctor if you notice any of the following side effects, especially if they don’t go away.

Estrogenic effects

With any hormone that involves androgen receptors, there will always be a risk of estrogenic effects.

This is because every time you introduce testosterone, they aromatize, which means they interact with the aromatase enzyme, which converts them to estrogen.

This interaction is very important to consider because, in other circumstances, you will need an AI (aromatase inhibitor) to lower your overall estrogen levels by shutting down the enzyme’s activity completely.

But in other cases, a SERM (selective estrogen receptor modulator) will act to prevent estrogen from binding to receptor sites by acting as a buffer.

They both do similar things, but the last option will be your first option, as it does not manipulate the full levels of hormones.

Estrogen will always be a risk factor, but monitor your levels because it can affect cholesterol, cause water retention, or even cause drastic changes in mood or personality.

Androgenic effects

Because it is such a powerful androgen, you should be aware of the side effects that are androgenic in nature.

These specifically assess the possibility of hair loss as testosterone is often converted to dihydrotestosterone, which is activated by the enzyme 5-alpha-reductase.

This in turn leads to things like increased skin oiliness, increased levels of hair loss, and acceleration of male pattern baldness if you are genetically predisposed to male pattern baldness.

There are 5AR inhibitors that can be taken, but because most androgenic side effects are not that serious, most men generally ignore these types of side effects.

Cardiovascular effects

Because most people suffer from common side effects that lead to a host of other problems in their cardiovascular system, it is important to know about them.

High blood pressure is wildly common with any new androgenic supplement, but you can reduce the chances of this happening if you can prevent water retention, which is closely related to estrogen levels in the body.

If you can control estrogen, you can surely contain serious effects of high blood pressure. If you are using low doses of nebido, you should not expect to see any major changes in your cholesterol levels.

However, if your cholesterol is borderline, then that could be a major problem that you should be very aware of. That is why when supplemented with nebide or any other androgen, it stays clean,


Fortunately, because nebido and other types of injectable hormones are not hepatotoxic, you won’t have to worry about any liver or organ damage.

Other effects:

  • Hypogonadism.
  • Fatigue.
  • Irritability.
  • Increased hemoglobin.
  • Insomnia.
  • Humor changes.
  • Aggression.
  • Erythema of the injection site.


Drugs that affect testosterone:

Barbiturates and other enzyme inducers: Interactions can occur with drugs that induce microsomal enzymes that can result in increased clearance of testosterone.

Effects of androgens on other drugs: Increased serum levels of oxyphenbutazone have been reported.

Oral anticoagulants: Testosterone and its derivatives have been reported to increase the activity of coumarin-derived oral anticoagulants, possibly requiring dose adjustment.

Regardless of this finding, the limitations of the use of intramuscular injections in patients with acquired or inherited irregularities of blood clotting should always be considered as a general rule.

Hypoglycemia: Androgens may enhance the blood sugar lowering effects of insulin. Therefore, it may be necessary to decrease the dose of hypoglycemic agents.

Interactions with other medications

If you take other medicines or over-the-counter products at the same time, the effects of the drug may change.

This can increase your risk of side effects or make your medicine not work properly. Tell your doctor about all medications, vitamins, and herbal supplements you are using, so your doctor can help you prevent or manage drug interactions.

Nebido may interact with the following medications and products:

  • Corticosteroids
  • Insulin.
  • Oral anticoagulants.

Can the nebide be detected?

Various steroids can be detected by drug tests. Although there is not much information on testing and screening for nebide, it is believed that the use of nebide could result in a positive drug test.

That being said, some bodybuilders and powerlifters may have found a way to inject themselves with nebide without it being detected by testing.

The detection time, compared to other steroids, is also believed to be longer, even if detected.

This means that the window between when nebido is first taken and when it is detected is extended, relative to other steroids.

Combination with other steroids

Proper nutrition, coupled with a work ethic, can give lifters a very nice physique. However, competitive bodybuilding may require more than just innocent weight lifting.

Steroids may need to be used to obtain your ideal result. Many weightlifters combine, or stack, steroids to meet their bodybuilding goal and build more muscle mass.

Using more than one steroid or supplement can be potentially dangerous.

Nebido is considered a strong steroid and should not be stacked with other powerful steroids. Some bodybuilders choose to stack nebido with milder and less potent steroids or steroids that are considered a bit safer to increase their results.

Although this is done quite frequently, a certified physician does not recommend the accumulation of drugs.