The permanent tattoo ink is usually deposited 1 to 2 millimeters into the dermis. And at this level it sometimes can cause more than artistic expression. Tattoo ink is a cocktail of metals and organic compounds and it interacts with body tissues. 

Though it is usually safe in some it may cause allergic reactions. It may take the form of raised bumps or blisters within 3 weeks. Most of these reactions are treatable with antihistamines or corticosteroids, but there are times when the tattoo may need to be removed. If the symptoms are chronic or worsening, diagnosis and treatment by a dermatologist is recommended.