Boldenone vs MK-677

Increased hematocrit and red blood cell count (the primary and most clinically significant side effect, more pronounced than with most other AAS)

Increased appetite (significant and dose-dependent, can be a benefit or hindrance depending on goals)

Anxiety and restlessness ('EQ anxiety' is widely reported anecdotally, particularly at higher doses or in anxiety-prone individuals)

Mild acne and oily skin (less than testosterone due to lower androgenic activity)

Suppression of endogenous testosterone production (profoundly suppressive, as with all AAS)

Mild hair thinning in genetically predisposed individuals (less than testosterone but not absent)

Elevated blood pressure secondary to increased blood volume from erythrocytosis

Increased vascularity (cosmetic effect, but indicative of elevated RBC)

Appetite stimulation (>50% of users)

Water retention (30-40%)

Lethargy (20-30%)

Fasting glucose elevation (5-15mg/dL)

Note on testosterone suppression: at doses up to 20 mg daily, MK-677 is unlikely to cause significant testosterone suppression on its own. Above 20 mg daily, the likelihood of suppression and other side effects (insulin resistance, water retention, lethargy) increases. The case report documenting 85.7% testosterone suppression involved co-administration with LGD-4033, a SARM known to be profoundly suppressive, making the SARM the likely primary driver of that suppression.