Rosacea

The exact cause of rosacea is unknown, although a number of potential factors have been suggested.

It's possible a combination of these factors may be responsible for the condition, although there isn't enough evidence to say this for certain.

Some of the main factors that have been suggested are outlined below.

Blood vessel abnormalities

Some experts believe abnormalities in the blood vessels of the face may be a major contributing factor for rosacea. This may explain symptoms of flushing, persistent redness and visible blood vessels.

It's not known what causes these abnormalities. But sun damage may be responsible for degeneration of the elastic tissue of the skin and the dilation of blood vessels.

Skin peptides

Recent research has shown external triggers such as ultraviolet (UV) light, spicy food, alcohol (particularly red wine), exercise, stress, heat and cold can lead to theactivation of certain molecules within the skin called peptides.

Increased levels of these peptides may in turn affect the immune system ornerves and blood vessels(neurovascular system) of the skin. Activation of these systems can cause dilation of blood vessels, redness and inflammation.

Microscopic mites

Microscopic mites called demodex folliculorum usually live harmlessly on human skin, but people with rosacea have particularly large numbers, which may play a role in the condition.

It is currently uncertain whether the mite is a cause or an effect of rosacea, although someresearchers have suggested the symptoms may be caused by the skin reacting tobacteria in the mites' faeces.

Helicobacter pylori bacteria

Helicobacter pylori bacteria are bacteriafound in the digestive system. It's been suggested these bacteria may be a possible cause of rosacea, althougha linkhasn't been proven.

One theory is the bacteria may stimulate the production of a protein called bradykinin, which is known to cause blood vessels to expand.

Genetics

Rosacea seems to be more common in families, although it's not clear which genes if any are involved or how they're passed on.

Triggers of rosacea

Although they're not thought to be direct causes ofthe condition, many people with rosacea find certain triggers make their symptoms worse.

Different people can have different triggers, but triggers that have been commonly reported include:

• exposure to sunlight
• stress
• hot or cold weather
• strongwinds
• strenuous exercise
• alcohol
• hot baths
• spicy foods
• hot drinks
• humidity
• caffeine found in tea, coffee and cola
• the Testosterone deficiency (hypogonadism)
• dairy products
• othermedical conditions
• certain medicines such as amiodarone, corticosteroids and high doses of vitamins B6 and B12