Testolone RAD-140 - Zyvex Pharmaceuticals

Frequently Asked Questions

• What is RAD-140 (Testolone) and how strong is it compared to other SARMs?

  RAD-140, generic name Testolone, is a selective androgen receptor modulator developed by Radius Health. Among the major SARMs, it has the highest anabolic-to-androgenic ratio - approximately 90:1 compared to testosterone's 1:1, Ligandrol's roughly 10:1, and Ostarine's approximately 3:1. This ratio means RAD-140 produces a high degree of muscle anabolic activity relative to the androgenic effects (scalp, prostate, skin) that cause androgenic side effects. In practical terms: it produces meaningful lean mass and strength gains at doses of 10-15 mg per day without the acne, hairline effects, or prostate stimulation that equivalent anabolic activity from testosterone would produce. The tradeoff is that higher anabolic potency comes with stronger HPTA suppression than milder SARMs like Ostarine, and PCT is required at standard performance doses.

• Does RAD-140 require PCT?

  Yes, at standard performance doses. This is one of the most frequently misunderstood aspects of RAD-140 use. The SARM category is sometimes marketed as "no PCT needed" - this is accurate for very low doses of mild SARMs like Ostarine, but it is not accurate for RAD-140 at 10-15 mg per day over an 8-12 week cycle. At these doses, testosterone suppression is real and measurable. Natural testosterone production drops significantly during the cycle as the androgen receptor activation from RAD-140 signals the hypothalamus to reduce LH and FSH release. After the cycle ends, this suppression persists until the HPTA recovers. Without PCT (Nolvadex or Clomid), recovery is slower, and the weeks of low testosterone that follow - fatigue, libido loss, mood disruption, muscle loss - undermine the gains made during the cycle. PCT starts 24-48 hours after the last dose: Nolvadex 20-40 mg/day for 4 weeks is the standard protocol.

• Does RAD-140 cause liver damage?

  There is a real hepatotoxicity concern with RAD-140, particularly at doses above 15 mg per day and in longer cycles. Unlike traditional oral anabolic steroids (Dianabol, Anadrol, Winstrol), RAD-140 is not 17-alpha alkylated - the modification that makes most oral steroids liver-toxic. However, case reports of cholestatic liver injury have been published in medical literature specifically associated with RAD-140 use, and liver enzyme elevations (ALT, AST) have been documented in user bloodwork at higher doses. The mechanism is not fully understood. The practical guidance: keep cycles to 8-10 weeks, avoid doses above 20 mg per day, avoid alcohol during the cycle, and run bloodwork that includes liver enzymes (ALT, AST) at mid-cycle if using 15 mg or above. Hepatotoxicity from RAD-140 at standard doses (10-15 mg) is uncommon but not impossible.

• Does RAD-140 cause hair loss?

  It can in genetically predisposed individuals, but at a lower rate than equivalent anabolic activity from testosterone. RAD-140's tissue selectivity means it produces less androgenic stimulation in androgen-sensitive tissues like the scalp compared to testosterone at an equivalent anabolic dose. However, it is not androgen-free. Users who are already experiencing male pattern baldness or who have strong DHT-sensitive genetics may notice accelerated hair thinning on RAD-140, particularly at doses of 15-20 mg. Unlike testosterone-based androgenic effects, this cannot be addressed with a 5-alpha reductase inhibitor (finasteride) because RAD-140's androgenic activity at the scalp is direct androgen receptor binding, not mediated through DHT conversion. The only reliable mitigation is using a lower dose (5-10 mg) or choosing a less androgenic SARM (Ostarine).

• What results can I expect from a RAD-140 cycle?

  At 10-15 mg per day over an 8-10 week cycle, most users report 5-8 lbs of lean muscle gain with simultaneous strength increases of 10-20% on major lifts. Unlike wet compounds (Dianabol, Deca), RAD-140 does not cause water retention, so the scale gains are closer to actual tissue than with aromatizing compounds. The physique effect is typically a harder, drier look rather than the full, pumped appearance of estrogen-driven mass. Strength increases often come before significant scale change - users commonly report notable strength improvement in weeks 3-4 before mass gains become visible. Gains are meaningful but more modest than equivalent cycles of testosterone or LGD-4033 at mass-focused doses - RAD-140 is not a replacement for an injectable AAS cycle for maximum mass. It is a serious tool for quality lean gains at a lower side effect cost than full AAS use.

• Can RAD-140 be stacked with other SARMs or peptides?

  Yes. Common stacks: RAD-140 with MK-677 (Ibutamoren) is the most popular combination - MK-677 stimulates GH pulsatility and increases IGF-1, complementing RAD-140's anabolic receptor activity without adding suppression or PCT burden (MK-677 is non-hormonal). This stack produces lean mass, improved recovery, and better sleep quality. RAD-140 with Cardarine (GW-501516) is used for cutting or recomp - Cardarine enhances fat oxidation and endurance while RAD-140 preserves muscle in a deficit. RAD-140 with LGD-4033 stacks the two most potent SARMs for a heavy lean bulking cycle - expect greater gains and greater suppression, requiring thorough PCT. RAD-140 with TB-500 or BPC-157 adds injury recovery support without any hormonal interaction. Stacking RAD-140 with anabolic steroids is also practiced: at moderate doses it serves as a highly anabolic addition without the estrogenic load of adding another aromatizing compound.

• Is RAD-140 legal to buy?

  RAD-140 occupies a gray area in most jurisdictions. It is not a controlled substance in the United States and most of Europe under current drug scheduling, and it is not FDA-approved as a pharmaceutical drug. It is sold as a research chemical or research peptide. It is explicitly banned by WADA and all major sports governing bodies for competition use - athletes subject to drug testing face disqualification and sanctions if it is detected. In the United States, the SARMs Control Act has been proposed in Congress but had not been enacted as of mid-2026 - check current regulatory status in your jurisdiction before purchasing. For non-competitive athletes purchasing for personal research, the legal exposure is generally low in most Western countries, but the regulatory environment is evolving and country-specific laws vary.

• Why was RAD-140 originally developed and what is its neuroprotective research?

  Radius Health developed RAD-140 for two medical applications: muscle wasting in cancer patients (where the tissue-selective anabolic effect would preserve muscle without androgenic side effects), and hormone receptor-positive breast cancer (where androgen receptor activation in ER+/AR+ tumor cells is antiproliferative - it can slow tumor growth). A third application emerged from preclinical data showing that RAD-140 activates androgen receptors in the brain and protects neurons against toxic insults, including beta-amyloid pathology relevant to Alzheimer's disease. This neuroprotective research led to Phase 2 clinical trials in Alzheimer's patients. For athletes, this research explains subjective reports of improved focus, motivation, and mood during a RAD-140 cycle - androgen receptor activation in the CNS has documented effects on these parameters, and RAD-140 crosses the blood-brain barrier and is active in neural tissue at the doses used for performance purposes.