Not all homeopaths agree on dosage and potency, but as a general rule, Chronic illnesses (. those that you've had for a long time) should be treated with low potencies (. 6x or 6C) and Acute conditions (. those that are relatively new) with high potencies (. 30x - 200c.) There are exceptions, particularly where an accident started off the symptoms and you might give the body a kick start with a high potency dose such as Arnica 200c first and then follow with a lower potency remedy.