Acne, commonly referred to as pimples, consists of comedones (black & white heads), inflammatory nodules and cysts. It is one of the most common skin conditions. Acne can affect any age group but it is most common in adolescents. Incidence is so prevalent in this group that is often referred to as a physiological condition.
Acne is caused by complex interaction of changing hormones, sebum, overgrowth of germs and inflammation. The description below is the cause of almost all cases of acne.
Increased sebum production:
We have oil producing glands called sebaceous glands just underneath the skin. They form part of the hair follicle (Pilosebaceous unit). These glands make oil called sebum which keeps the skin supple and smooth. Sebum comes out on the skin surface through the same pore as the hair.
During teenage years, due to hormonal changes sebaceous glands are stimulated resulting in more sebum production. This results in oily skin and higher incidence of acne.
Clogging of pores:
Skin consists of 3 layers. The outer layer is called epidermis and consists of dead cells. These cells rise to the surface and the body shed them. When the body produce lot of sebum, dead skin cells stick together inside the pore resulting in clogging of the pore causing comedones. If the pores are open, they are called blackheads and if closed they are known as white heads.
Bacterial colonisation and inflammation:
Skin is colonised by diverse microorganisms most of which are harmless or even beneficial to their hosts. They are called commensals. Propionibacterium acnes is one of them.
Trapped sebum, due to clogging of pores is ideal for Propionibacteria to multiply. Immune system reacts to large number of this bacteria resulting in release of inflammatory cells causing inflammation. Thus, skin becomes red and painful. The acne lesion(pimple) becomes larger and filled with pus (pustule). In some cases, pustules, can grow to form small nodules and cysts.
Causes of acne flare up:
- Picking and squeezing the acne lesions cause further inflammation and scarring.
- Thick or greasy make up possibly make acne worse by blocking the pores. It is better to use oil free products (non-comedogenic) in acne prone skin.
- Contraceptive pills containing progesterone only make acne worse.
- Excessive sweating or humid conditions may make acne worse.
- Creams containing corticosteroids can make acne worse.
- Oral medications like anti epileptics can cause acne flare up.
- Hormonal abnormalities as seen in Polycystic ovarian syndrome (PCOD) can cause acne or leads to flare ups.
- It is thought that some foods especially diet high in sugar and milk products cause acne flare up but research has found no evidence to support this.
I hope this article helped you to understand causes of acne. In the next article, I will discuss the treatment of this skin condition.