Long‑term low testosterone can zap your energy, mood, and muscle. Testosterone undecanoate steps in as a slow‑and‑steady helper, giving your body the hormone it’s missing without the roller‑coaster spikes some older treatments cause. The drug comes in both shots and easy‑to‑take capsules, so you and your doctor can match the form to your lifestyle.
What makes this medicine stand out is its “undecanoate” tail, a long fatty chain that lets the hormone drip out slowly. That means fewer clinic visits if you choose the shot and less strain on your liver if you go with the capsule. By the end of this guide you’ll know how it works, the good it can do, the red flags to watch for, and the questions to ask your healthcare team.
Key Takeaways
- Testosterone undecanoate offers long-lasting hormone support, with injections lasting up to 10 weeks and oral capsules taken twice daily.
- Oral TU bypasses liver strain by absorbing through the lymphatic system, reducing potential liver-related side effects.
- Injections may cause rare but serious reactions like POME and anaphylaxis, necessitating a 30-minute observation post-injection.
- Regular blood tests are essential to monitor testosterone levels and adjust dosages, ensuring optimal benefits and minimizing risks.
- Not suitable for women, children, or those with certain health conditions; misuse can lead to serious health complications.
Table of Contents
Understanding Testosterone Undecanoate
A Long‑Acting Ester
Forms You Can Choose
- Injection (Aveed/Nebido). A 3 mL (750 mg) deep‑gluteal shot is given on day 0, at week 4, then every 10 weeks. That schedule keeps blood levels in the normal zone with only five or six visits a year
- Oral Capsule (Jatenzo). Taken with food, it starts at 237 mg twice daily, then titrates between 158 mg and 396 mg based on lab tests drawn six hours after your morning dose.
How It Travels in Your Body
Injected TU sits in muscle oil and seeps into the blood, while oral TU rides through intestinal lymph rather than the liver, sparing first‑pass strain. Both routes deliver free testosterone that binds to androgen receptors, boosting muscle protein, red‑blood‑cell production, and sexual health.
Who May Need It
Doctors prescribe TU for adult men diagnosed with hypogonadism as confirmed by two separate morning tests showing low testosterone plus symptoms such as fatigue, low libido, or loss of bone mass. It is not approved for bodybuilding, age‑related “anti‑aging,” or use in women or kids.
Benefits, Dosage, And Safety
Why You Might Like TU
- Steady Levels: Fewer peaks and crashes mean more consistent mood, energy, and sexual function.
- Convenience: Injections every ten weeks or capsules you can swallow with breakfast—no messy gels or daily patches.
- Lower Liver Impact: Oral TU bypasses most liver metabolism via lymphatic absorption, unlike older 17‑alpha‑alkylated tablets.
Dosage Checkpoints
Injectable dosing rarely needs adjustment, but your provider will still test trough levels before your next shot. Oral dosing is personalized: labs at day 7 or after any change keep total testosterone in the 400-700 ng/dL window. Take capsules with a fat‑containing meal for best uptake.
Possible Side Effects
- Injection‑specific: Pulmonary oil micro‑embolism (POME) events—cough, chest tightness—plus rare anaphylaxis moments after the shot.
- General androgen effects: Acne, higher red cell count, mood swings, sleep apnea, and prostate‑specific antigen (PSA) bumps.
- Oral‑specific: Higher blood pressure and ankle swelling reported in some studies. Regular monitoring is key.
Safety Rules
Never start TU without two low testosterone labs. Avoid it if you have prostate or breast cancer, uncontrolled heart disease, or plan to father a child soon—high T can lower sperm counts. Check hematocrit, lipids, liver enzymes, and PSA at baseline, at 3-6 months, then yearly.
Take Charge Of Your Testosterone Health
Frequently Asked Questions
Most men notice energy and libido lift within 3–4 weeks, with muscle and mood gains by three months.
The shot is deep and thick, so mild soreness happens, but proper technique and rotating sides reduce pain.
High testosterone can tell your brain to slow sperm production. If kids are in your plans, discuss sperm banking first.
Take it with your next meal; don’t double up. Consistency matters for steady levels.
No. Testosterone undecanoate is not approved for women and can harm a developing fetus.
Many plans cover FDA‑approved TRT after documented low T and symptoms, but co‑pays vary.
Hypogonadism is often lifelong. You’ll keep using TU as long as benefits outweigh risks and labs stay safe.
