Acne varies in severity from person to person. Individual sufferers may notice periods when their symptoms improve and other times when they flare up. The number of acne lesions, and how painful and inflamed they are, helps to determine the severity of the condition so that the right treatment option can be recommended.

NHS Choices suggests the following guidelines to measure the severity of the condition:

• Grade 1 (mild) €“ mostly whiteheads and blackheads with only a few papules or pustules
• Grade 2 (moderate) €“ a number of papules and pustules that mostly occur on the face
• Grade 3 (moderately severe) €“ a large number of papules and pustules, plus some inflamed nodules. The face, back and the chest are often affected
• Grade 4 (severe) €“ a large number of painful pustules or nodules.

As well as the psychological effects that acne can cause, physical complications can also sometimes occur, particularly in more severe cases:

• Scarring €“ severe acne can lead to permanent scarring, which is visible even after the acne lesions have healed. Scarring usually results from deep lesions, such as cysts
• Hyperpigmentation €“ darkening of the skin can occur with severe acne, especially if it was inflamed. This more often occurs in people with darker skin.

Such complications explain why people with severe acne lesions should seek treatment and not let the condition 'run its course'.