A clogged milk duct can be identified by several signs and symptoms. The main sign is a painful, tender lump in the breast, which may feel hard or sore when touched. The area around the lump might be red or irritated and can sometimes be visible. The breast may also feel full or engorged even after feeding or pumping. Some people notice a small white spot on the nipple (called a milk bleb) which can be associated with a clogged duct. Other symptoms can include localized warmth, discomfort during breastfeeding, and in some cases, thickened or stringy milk expression. If flu-like symptoms such as fever, chills, or body aches occur, it could indicate mastitis, a related infection and a more serious condition requiring medical attention. In summary, to know if there is a clogged milk duct, look for a tender lump in one area of the breast, pain or soreness, redness or warmth in that area, and persistent fullness despite milk expression. If symptoms worsen or include fever, seek healthcare advice promptly.