Low Testosterone Does NOT Directly Affect Semen Color or Thickness
Low testosterone levels are not associated with changes in semen color or thickness. The comprehensive AUA guidelines on testosterone deficiency and multiple clinical studies examining the relationship between testosterone and semen parameters make no mention of semen color or viscosity as symptoms or signs of hypogonadism 1.
What Low Testosterone Actually Affects
The established clinical manifestations of testosterone deficiency include 1:
- Sexual symptoms: Reduced libido, erectile dysfunction, decreased spontaneous erections
- Physical signs: Changes in body hair patterns, gynecomastia, reduced muscle mass, increased body fat, testicular atrophy
- Systemic symptoms: Fatigue, reduced energy, diminished work performance, depression, poor concentration, irritability
- Metabolic effects: Anemia, bone density loss, insulin resistance 1
Testosterone and Semen Parameters: What the Evidence Shows
While testosterone is essential for spermatogenesis, its relationship to measurable semen characteristics is complex 2, 3:
- Sperm count and motility: Low testosterone is associated with reduced sperm production and motility, but this affects the cellular components of semen, not its physical appearance 2, 4, 5
- A large study of 853 men undergoing IVF found that those with low testosterone (<264 ng/dL) had lower sperm counts and motility, but no mention was made of color or consistency changes 2
- Seminal plasma testosterone and dihydrotestosterone concentrations may influence sperm quality, but again, this relates to sperm function rather than semen appearance 6
Common Clinical Pitfall
Do not confuse changes in semen volume with changes in color or thickness. Hypogonadism can affect semen volume through its impact on accessory gland function, but this is distinct from viscosity or color 1. Semen color and consistency are primarily determined by:
- Prostatic secretions (milky-white appearance)
- Seminal vesicle contributions (gel-like consistency)
- Liquefaction enzymes
- Presence of infection, blood, or other pathology—none of which are caused by low testosterone alone
What Actually Changes Semen Appearance
Changes in semen color or thickness should prompt evaluation for 1:
- Infection (yellow/green discoloration, increased viscosity)
- Hematospermia (blood in semen—pink/red/brown color)
- Prolonged abstinence (increased viscosity, yellow tint)
- Dehydration (thicker consistency)
- Ejaculatory duct obstruction (low volume, thick consistency)
None of these are direct consequences of low testosterone levels.