Androgenetic Alopecia (Male Pattern Baldness): This is the most common cause of hair loss in young males, characterized by a receding hairline and thinning of hair on the vertex of the scalp. It is due to the sensitivity of scalp hairs to dihydrotestosterone (DHT), a potent form of testosterone.

Alopecia Areata: An autoimmune condition that leads to patchy hair loss. It can occur at any age and is often associated with other autoimmune diseases.
Telogen Effluvium: A condition that causes excessive hair shedding after a major body stress, such as severe illness, psychological stress, or major surgery. It can also be triggered by hormonal changes.
Tinea Capitis (Ringworm of the Scalp): A fungal infection that causes hair loss, often accompanied by redness, itching, and scaling of the scalp.
Seborrheic Dermatitis: A skin condition that can cause scaly patches, red skin, and stubborn dandruff, leading to hair loss if left untreated.

Thyroid Disorders (Hypothyroidism or Hyperthyroidism): Both underactive and overactive thyroid glands can cause hair loss among other symptoms. Early detection is crucial for treatment and prevention of long-term complications.
Syphilis: A sexually transmitted infection that can cause hair loss in its secondary stage, along with other systemic symptoms.
Autoimmune Disorders (e.g., Lupus): Systemic lupus erythematosus and other autoimmune diseases can cause hair loss as part of their broader symptomatology.

Trichotillomania: A psychological disorder characterized by an irresistible urge to pull out one's own hair, leading to noticeable hair loss.
Loose Anagen Syndrome: A rare condition where the hair follicles are abnormal, leading to excessive hair shedding.
Congenital Hair Loss Conditions (e.g., Congenital Atrichia): Extremely rare conditions present at birth that result in little to no hair growth.
Hair Loss due to Medication Side Effects: Certain medications, such as those used for cancer, arthritis, depression, and high blood pressure, can cause hair loss as a side effect.