Why is Acne on back difficult to treat?

There are many factors responsible for difficulties in treatment of acne on back.
These are related to either the acne on back sufferer or to the disease itself.
Factors related to the disease are either quantitative or qualitative.
Quantitative factors are considered in association with: large pores, large surface area with increased skin thickness and toughness and the extent of lesions.
The large pores of sebaceous glands on the human back are responsible for the more severe-looking appearance of some back acne lesions and its need for more treatment.
The skin of the back is thicker than anywhere else in the body; accordingly ducts of sebaceous glands need to penetrate it for a longer distance to reach the pores located at the skin surface. This feature promotes relative stagnation and clogging of the sebum inside the ducts. Since the back has much tougher skin than the face, commonly available topical treatments used for facial acne are not sufficient, it would therefore need stronger solutions of up to10% benzoyl peroxide. At times it is more resistant to treatment and some dermatologists may recommend using benzoyl peroxide in conjunction with another form of back acne treatment, such as glycolic acid or salicylic acid.
The late discovery of acne lesions is usually associated with their widespread distribution all over the back.
Qualitative factors include: type of lesions; mostly nodulocystic, prevalence of bacteria; secondary to increased humidity and the relatively diminished blood supply of the back which reduces the rate of healing.
Increased thickness of back skin favors the development of nodules and the deeply seated cysts commonly encountered in acne on back. The nodulocystic form is known to be more difficult to control than comedones.
The bacterial element (p.acnes), a normal inhabitant of the skin surface and known to contribute to the disease process is also enhanced; simply due to the large surface area, the humidity resulting from sweating. This fact has its implications on antibiotic therapy of acne lesions.
The healing process also entails adequate blood supply for repair and renewal of exfoliated skin. This point explains why acne on back takes more time for healing in comparison to facial acne.

Factors related to the acne on back sufferer are: late discovery of lesions, difficulty to apply topical medications specified for acne on back lesions, and clothing factors.
The invisible back hinders perception of acne lesions. Late discovery of the lesions of acne on back (usually when severe or complicated) and therefore difficulties in its treatment.
The remote back is partially beyond the the range of movements of the upper limb and the reach of the fingers. The main disadvantage of the remote back is the difficulty or inability to apply topical medications specified for acne on back lesions. The sufferer is always in need for the help of a family member and that is a drawback in both treatment and patient compliance.
Back coverage and the necessity of clothing may be associated with staining due to contact with medications, deprivation of the beneficial drying effect of sunlight and in severe cases preventing from going out as the sufferer is unable to keep clothing on the body.
Many acne medications contain benzoyl peroxide, which is very effective for fighting acne. Using benzoyl peroxide may stain clothing, much like bleach. This upsets the emotionally fragile sufferer and adds to the psychological impact.
Back coverage hinders moderate exposure to ultraviolet rays of sunlight which helps in drying of acne on back lesions.
In severe cases of back acne, it might even make it difficult for the person to keep clothing on the body and this might make the person’s movement handicapped.
All these patient relate factors reduce compliance of the acne on back sufferer and contribute to difficulty in treatment.