These invasive procedures pose the possibility of blood-borne diseases. According to many health experts, hepatitis, especially hepatitis B, is the greatest threat from body piercing. Hepatitis B can be transmitted in as little as 0.00004 ml of blood. This is a hardy virus and can survive on instruments, doorknobs, etc., for many days or even weeks. It says piercing always carries a risk of infection, but that risk is greater with mouth piercing because of the closeness of the airway.
Infection can cause the tongue to swell, blocking or restricting the airway.
In addition, bacteria under the tongue often spreads quickly and can lead, in extreme cases, to the potentially fatal toxic shock syndrome or blood poisoning. The BDA also says that a person can develop an allergic reaction to a stud if it is not made from gold, titanium or surgical steel. Body piercing has been blamed for a steep rise in allergies to nickel across the Western world. Exposure to the metal can cause lifelong sensitivity. A nickel allergy can occur at any age.