I applied Dettol on my skin and now the area around it has darkened. Its also causing some irritation. Will the darkening fade away on its own or do I need to do something about it?

It sounds like you may be experiencing a skin reaction to the Dettol. To help with the irritation and darkening of the skin, you can try using a mild steroid cream like Hydrocortisone 1% cream. Apply a thin layer on the affected area twice a day for up to 7 days. Additionally, you can use a soothing moisturizer like Cetaphil to help hydrate the skin. If the symptoms persist or worsen, please consult a doctor for further evaluation and management.