Variously called Death Day, Decision day, and a number of other less kind words, D-Day was the day that the Allies began the big push from the coast of France all the way to the heart of Germany, ending WWII.
More importantly when it comes to cystic acne, tea tree oil can be harmful to your skin when applied in high concentrations. Some individuals have reported severe skin irritation and allergic dermatitis after applying too much tea tree oil, or applying the proper dose too frequently.
Tea tree oil may also be able to help with your acne. In one study, 30 people used tea tree oil gel for 45 days, and another 30 people used a placebo. Those who used the gel saw greater improvements in their acne. Tea tree oil is a good alternative to benzoyl peroxide, a well-known ingredient in acne creams.