ADELPHI PROVIRON 25mg 30 TABS

Adelphi Research Proviron (Mesterolone) 25mg is a unique oral DHT-derivative that enhances the effects of other steroids in a stack by reducing SHBG, increasing free testosterone, and providing a cosmetic hardening effect without the liver toxicity of standard oral steroids. Unlike most oral compounds, Proviron is not C17-alpha alkylated, meaning it does not stress the liver. It is not a mass builder on its own but acts as a powerful “force multiplier” that makes every other compound in your cycle work harder.

How Proviron Works

Proviron’s primary mechanism is its exceptional affinity for sex hormone-binding globulin (SHBG). SHBG is a protein in the bloodstream that binds to testosterone, rendering it inactive. When SHBG levels are high, a large percentage of your circulating testosterone (natural or exogenous) is “locked up” and unavailable for muscle building. Proviron binds to SHBG with very high affinity, freeing up testosterone and other anabolic hormones to interact with androgen receptors in muscle tissue.

Research confirms that Mesterolone reduces SHBG levels by 20-40% at standard therapeutic doses, significantly increasing the bioavailable fraction of total testosterone. In practical terms, this means 500mg/week of testosterone produces more muscle-building effect when Proviron is added to the cycle, even though the injected dose remains the same.

Proviron also has mild anti-oestrogenic activity. As a DHT derivative, it competes with testosterone for the aromatase enzyme but cannot itself be converted to oestrogen. This provides a subtle oestrogen-lowering effect that reduces water retention without the aggressive oestrogen suppression of a full aromatase inhibitor. Many users describe the look as “drier” and more defined when Proviron is added, particularly in the final weeks of a cutting phase.

Suggested Protocol

• On-cycle use (most common): 25-50mg per day alongside injectable testosterone or other compounds. Split into 2 doses (morning and evening)
• Pre-contest / cutting: 50-75mg per day for the final 4-6 weeks for hardening and drying effects
• Duration: can be run for the entire length of a cycle (8-16 weeks) because it is not liver-toxic
• Stacks especially well with: Testosterone Enanthate (amplifies free Test), Stanavar or Winstrol (enhanced cutting synergy), Masteron (complementary DHT-based hardening)

What Proviron Does NOT Do

It is important to set correct expectations. Proviron is not a mass builder. It will not add 5 kg of muscle on its own. It does not significantly increase protein synthesis in the way that testosterone, Dianabol, or Trenbolone do. Its value is entirely in amplifying other compounds and providing cosmetic finishing effects. Think of it as a performance enhancer for your performance enhancers.

Side Effects

• Liver toxicity: none. Proviron is not C17-alpha alkylated, making it safe for extended use
• Hair loss: moderate-high risk. As a pure DHT derivative, it directly accelerates male pattern baldness in genetically predisposed users. This is its most significant downside
• Testosterone suppression: mild at 25-50mg/day but present. PCT is still required after a cycle that includes Proviron
• Acne: possible due to DHT activity. Manageable with standard skin care
• Cholesterol: minimal impact compared to C17-aa orals. Much less lipid-disruptive than Winstrol or Anavar
• No water retention, no gynecomastia risk (DHT cannot convert to oestrogen)

Proviron vs Masteron

Both are DHT derivatives used for hardening and anti-oestrogenic effects:

• Proviron: oral, no liver toxicity, primarily works via SHBG reduction, mild cosmetic hardening, convenient daily tablet
• Masteron: injectable, stronger cosmetic hardening and muscle density, more effective at very low body fat, requires frequent injections (EOD for Propionate ester)
• Many users run both simultaneously in a cutting stack for maximum effect

Key Facts

• Active ingredient: Mesterolone 25mg per tablet
• Manufacturer: Adelphi Research
• Tablets per pack: 30
• Anabolic / Androgenic: 100-150 / 30-40
• Half-life: 12 hours
• Aromatisation: none (acts as mild anti-oestrogen)
• C17-alpha alkylation: no (not liver-toxic)
• SHBG reduction: 20-40%

For a complete side-effect breakdown, read our Steroid Side Effects Guide. Browse all oral steroids. For PCT after your cycle, see our PCT Guide.