DermalMD Acne Serum is generally safe for sensitive skin as it contains natural and gentle ingredients like witch hazel, salicylic acid, and tea tree oil. These ingredients are known for their anti-inflammatory and antibacterial properties which can help to combat acne. However, everyone's skin is different and may react differently to the same product. Even though the ingredients are gentle, it is always a good idea to do a patch test before applying it to your entire face. To do a patch test, apply a small amount of the serum to a small area of your skin that's easy to conceal, like your forearm. Wait 24 hours to see if you have any reaction. If you experience redness, itching, or other irritation, it may not be suitable for your skin. If you pass the patch test without any adverse reactions, you can start using the serum on your acne. As for usage, it is typically recommended to apply the serum once or twice daily, but you should follow the instructions provided by the manufacturer or your dermatologist. If you notice any skin irritation or worsening of your acne after using the serum, discontinue use and contact your dermatologist for further advice.