Biotin deficiency symptoms include hair thinning, skin rashes, and fatigue

Biotin deficiency can cause hair thinning, skin rashes, and chronic fatigue. The essential B vitamin, also known as B7, aids energy conversion. Symptoms include hair loss, brittle nails, and a red, scaly rash around the eyes, nose, and mouth. Neurological issues like irritability, depression, and tingling can occur. Muscle pain, nausea, and developmental delays in infants are also possible.