The condition generally referred to as rickets is most commonly nutritional vitamin D deficiency rickets, a type of nutritional disease that is prevalent among infants and young children, particularly very young babies. It primarily manifests as changes in the bones where growth is most rapid and can also affect muscle development and changes in nervous excitability. Initially, especially within the first three months, symptoms in very young infants typically include increased nervous excitability, such as crying easily, excessive head sweating, and as a result of the sweating, frequent head shaking, irritability, restlessness, and noticeable crying and restlessness at night. These symptoms at this stage are not necessarily indicative of typical rickets.

As the condition progresses, changes in the skeleton gradually become apparent. In infants under six months with rickets, the changes are mainly in the skull, typically feeling like pressing on a ping-pong ball. After six months of age, the head shape becomes squared or box-like, and the head circumference is larger than normal. Later, the characteristic beading changes of rickets appear, with beaded protrusions above the ribs, followed by the formation of blunt, circular raised areas at the wrists and ankles, referred to as wrist and ankle bracelets. Around the age of one, infants may develop a deformity resembling pigeon chest. As the child begins to stand and walk, the weight bearing on the lower limbs may lead to deformities, such as bowlegs or knock-knees, and sometimes even K-shaped deformities of the legs, and some might develop spinal deformities.