Repeated swelling and shrinkage of the cuticle cause damage, hair breakage and split ends. Chemicals used in straightening and hair relaxing break the disulphide bonds for the desired longer lasting effect. Such chemical treatments should not be done more than once or twice in a year. The treatments are best avoided in weak, thin slow growing hair. it is advised to pre condition your hair with 2-4 months of nutritional regimen before subjecting to any chemical treatments.