One of the best antiseptics for an infected ingrown toenail is Povidone-iodine. The most common brand name for this antiseptic in Australia is Betadine, and it can be found at your local pharmacy or most supermarkets. Be sure to choose the liquid version and not the gel; the liquid preparation can seep around the nail edge and into the sulci more effectively as well as act as an astringent (drying effect). Many ingrown toenails can start or be perpetuated by too much moisture in the sulci, so a liquid with a drying effect is going to be more effective than a cream based antiseptic.
A warm salt water soak can be used in conjunction with Povidone-iodine and adds to the overall effectiveness of combating a local infection.
The toenail piercing the adjacent skin is what leads to infection, so if the nail hasn’t been addressed (trimmed back or smoothed out), or other causes eliminated (such as narrow or tight fitting shoes), antiseptic treatment will likely only serve to control the infection rather than fully eliminate it.
Be sure to address the causes of your ingrown toenail so the antiseptic can do its job best!