Different physical reactions to tattooing have been reported by medical professionals in America and Britain, and although not a major issue in any way, it is important to discuss. Most reactions are due to allergies to the latex gloves worn by tattoo artists, sensitivities to metals within the tattoo ink, infections caused by unclean practices, and sun exposure.
If you are allergic to latex, you need to make your tattoo artist aware before the day of your tattoo appointment. This will give them time, if needed, to purchase a synthetic version. An allergic reaction to latex may not be apparent at the time of your tattoo, but can lead to excess swelling and irritation later. Although this reaction is rarely strong enough to cause serious physical issues, it can cause your tattoo to heal in an unsatisfactory way, and even cause scarring.
Most people with metal sensitivities, especially mercury, have reactions or irritation for prolonged periods of time after getting tattooed. The color red is considered the biggest culprit for metal reactions. These reactions can leave the skin itchy and sore for months or even longer. Some people can develop a sensitivity to mercury that they did not previously have because of the tattoo. Your doctor can prescribe topical creams that are able to take away any discomforts related to metal sensitivity.
Infections, while not common, can be a difficult problem to not only cure, but to pinpoint the actions that caused them. You may have gotten infected by something your tattoo artist did, or something you did on your way home, or while trying to heal your tattoo. You should keep your tattoo absolutely clean for the first few days of healing, keeping it away from germ infested areas and objects like diapers, litter boxes, stagnant water, etc. You will be able to tell that you have an infection by discoloring of the tattoo or the skin around the tattoo. If the surrounding skin becomes red or inflamed, you should bring it to the attention of a doctor.
New tattoos are sensitive, and need to be protected from the elements. This means that prolonged exposure to the sun will damage the new tattoo, and cause soreness, swelling, and/or it will become hot to the touch. New tattoos also need to be safe from extreme temperatures. This includes water temperature, so take precautions when washing your tattoo that the water not be too hot. Also keep your tattoo from being rubbed or bumped, as too much friction will cause damage to your permanent body art.