Testosterone Phenylpropionate 100mg/ml is a fast-acting injectable androgen and anabolic steroid (AAS). It is commonly used in hormone replacement therapy (HRT) and performance enhancement.

In addition, it is an esterified form of testosterone. Its phenylpropionate ester controls its release rate. As a result, it acts faster than long esters like cypionate or enanthate.

At 100mg per milliliter, it provides moderate potency and a predictable response. Moreover, its half-life is about 4–5 days. Therefore, injections are usually required every 2–3 days to keep stable testosterone levels.

This frequent schedule differs from longer esters, which often require weekly dosing. However, it allows faster adjustments and quicker cycle control.

Medically, it may be prescribed for hypogonadism, delayed puberty, and certain breast cancer cases in women. Typically, HRT dosing ranges from 50–100mg every 4–5 days, depending on symptoms and blood levels.

Compared to longer esters, it allows more precise dose changes. Consequently, it may reduce prolonged hormonal suppression after stopping treatment.

In bodybuilding contexts, it is sometimes used in short cycles of 6–8 weeks. It can also be used as a front-loading compound with slower esters. Common weekly doses range from 300–500mg, split into multiple injections.

Like all testosterone esters, it suppresses natural testosterone production. Therefore, post-cycle therapy (PCT) with SERMs such as tamoxifen or clomiphene may be required.

Finally, the 100mg/ml concentration is less common than higher strengths. As a result, it may require larger injection volumes, which can increase local irritation.