The scientific name for garlic is Allium sativum. Crushed garlic has been used for millennium for a host of medical problems, both systemic (taken by mouth) and skin conditions (applied on topically on the skin). Application to the skin, for a host of problems is not without sound medical judgment, but is misguided.
It is true that topical garlic is anti-microbial, anti-fungal and antiviral. In addition, garlic can arrest bleeding when applied to a fresh wound, decrease pain and promote healing. Unfortunately, crushed garlic contains a powerful botanical chemical called diallyl disulfide. As a result, when crushed garlic is rubbed on the skin, it can not only potentially cause irritant dermatitis but it has been reported to actually burn the skin. A garlic necklace or wreaths have been placed upon the neck of children for nasal congestion and abdominal pain. This has also been reported to result in severe neck burns. Similarly, individual have burned their children face when garlic paste was applied to the face for itchy eczema. Also see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2798796/
Factors which increase the risk of garlic burns include fresh garlic, increase time of contact with the skin, pre-existing skin dermatitis or sensitive skin. In addition, handling garlic with the hands can cause allergic contact dermatitis, a poison ivy type of dermatitis. The later is particularly seen in chiefs and other food handlers. Other vegetables may cause allergic contact dermatitis, including asparagus, carrot, celery, cow-parsnip, cucumber, Indian beans, mushroom, onion, parsley, tomato, and turnip. Allergic contact dermatitis to onion is much less common than seen secondary to garlic.
Garlic burns are best treated like thermal burns. If blisters develop after garlic contact with the skin, they should not be broken but allowed to act as a natural biological dressing. Oreganknow healing ointment should be applied on the burn area 2X per day. The area should be covered with a lightly applied Telfa pad. Afterwards, always check if you are up to date with tetanus vaccinations.
Garlic taken by mouth is a different matter. It has been shown to boost the immune system to fight off infections such as a cold. It has been shown to lower blood pressure, lower cholesterol levels and perhaps lowers the risk of coronary heart disease.