What Causes Rosacea


At Riversol we take research seriously.  Below we have reviewed the most credible research available to help you understand exactly what causes rosacea.  Feel free to contact us if you have any questions.

Figuring out exactly what causes rosacea is the first step to finding an appropriate treatment for rosacea.  Currently there is no cure for rosacea and exactly what is responsible for the development of rosacea remains unknown1,2.  Extensive research has given life to five leading theories:

  1. Problems with your immune system
  2. A reaction to microorganisms
  3. Sun exposure
  4. Inappropriate blood vessel function
  5. Genetics

1. Problems with Your Immune System

When your immune system isn't functioning well, it could lead to the development of rosacea by creating abnormal proteins. These proteins affect the way blood vessels work and can cause redness or swelling (inflammation). An increased number of these proteins have been seen in the skin of patients suffering from rosacea4. A study where proteins from patients with rosacea were injected in mouse skin, led to redness or swelling and widening of blood vessels. This provides evidence in the development of rosacea. The human immune system protects skin from microorganisms, damage from the UV rays, and also physical or chemical injury3. Problems with the human immune system can lead to long-term swelling or redness (inflammation), and blood vessel dysfunction seen in rosacea.

2.  A Reaction to Microorganisms

Reactions to germs on the skin may be the cause of skin redness or swelling. There are a number of different germs or microorganisms that are the cause:

Demodex Mite and Bacillus Oleronius

Demodex is a mite that resides in the skin of almost everyone; they are found in greater numbers in patients with rosacea5. Patients with subtype 2 rosacea have been found to have a much greater immune response to a bacteria (bacillus oleronius) found in Demodex.  The way in which Demodex causes rosacea may be due to a combination of factors. These factors include a reaction to the proteins produced by bacillus oleronius, an allergic reaction to Demodex and / or other microbes that may be associated with Demodex mites.  Additionally, new evidence also points to infestation of Demodex Mites as a cause for ocular rosacea. 

Helicobacter pylori

Most commonly known for its role in acid reflux (heart burn), this bacterial infection in rosacea is debatable.  Studies reporting improvement in rosacea after taking antibiotics for H. pylori could be explained by the anti-inflammatory effects of the antibiotics used for treatment6. As a result, the role of this bacterial infection in rosacea is not confirmed.

Staphylococcus epidermidis7,8, chlamydia pneumoniae9, and small intestine bacteria10

These three microorganisms have been introduced as a cause of rosacea in several studies. More research is needed to determine if any of these cause rosacea.

3. Sun Exposure

sun exposure

Ultraviolet rays from the sun are often recorded as a trigger for rosacea.  This is mostly because of the presence of rosacea on severe sun-exposed skin, signs of sun damage on rosacea skin tests, and a greater incidence of rosacea in fair-skinned people.

There are a number of theories on why sun exposure can promote rosacea. UVB radiation has been shown to promote blood vessel growth in mice. UV rays also produces harmful chemicals, and may have a negative effect on the immune system3.

A link between all the different sub-types of rosacea and UV rays has not been found and less than one-third of patients with rosacea report the triggering of their symptoms with sun exposure11. A study from Korea involving 168 rosacea sufferers found that greater sun exposure shows more blood vessels, redness, and flushing. However, it did not affect patients with subtypes 2,3 and 4 rosacea.

Extremes of temperature can worsen rosacea. Therefore, heat , UV rays or a combination of both (from prolongued exposure to the sun) can be responsible for the worsening of rosacea. 

4. Inappropriate Blood Vessel Function

Facial flushing is common in rosacea and is also associated with worsening rosacea. Blood flow increases in the skin of some rosacea patients13. This means overactive blood vessels could be a cause of rosacea3.

Overactive blood vessels link to abnormalities of the nerves that control them.  The normal process responsible for controlling heat may cause flushing in rosacea11

It is not known if rosacea is more common in people with migraines (also related to abnormal workings of blood vessels)14. One study saw a slight increase in rosacea among women, but did not show a relation between migraines and rosacea in men14.

5. Genetics

People with a family history of rosacea are more likely to develop the disorder15. However, at this time genes related to an increased risk for rosacea have not been identified.

6. External Triggers

For most with rosacea (over 90%), the number of rosacea flare-ups can be reduced by avoiding the combination of environmental and lifestyle factors that trigger their symptoms. What causes a rosacea flare-up in one person may not affect another. Thus, understanding and avoiding your personal triggers is an important step in managing rosacea symptoms.

The triggers most commonly identified include:

  • Sun Exposure (81%)
  • Emotional Stress (79%)
  • Hot weather (75%)
  • Wind (57%)
  • Intense Exercise (56%)
  • Alcohol (52%)
  • Spicy foods (45%).

One method of discovering your personal rosacea triggers is to keep a daily rosacea journal; keep track of environmental and lifestyle factors while observing your rosacea symptoms on a daily basis. Track and record weather conditions, foods and beverages consumed, exercise, stress level, products used on the face, medications, and anything that causes flushing (such as hot showers or baths). There are even tracking apps available for smartphones.

Click here to see our complete guide to rosacea treatment


  1. Mc Aleer MA, Lacey N, Powell FC. The pathophysiology of rosacea. G Ital Dermatol Venereol 2009; 144:663.
  2. Dahl MV. Pathogenesis of rosacea. Adv Dermatol 2001; 17:29.
  3. Yamasaki K, Gallo RL. The molecular pathology of rosacea. J Dermatol Sci 2009; 55:77.
  4. Yamasaki K, Di Nardo A, Bardan A, et al. Increased serine protease activity and cathelicidin promotes skin inflammation in rosacea. Nat Med 2007; 13:975.
  5. Zhao YE, Wu LP, Peng Y, Cheng H. Retrospective analysis of the association between Demodex infestation and rosacea. Arch Dermatol 2010; 146:896.
  6. Tan J, Berg M. Rosacea: current state of epidemiology. J Am Acad Dermatol 2013; 69:S27.
  7. Whitfeld M, Gunasingam N, Leow LJ, et al. Staphylococcus epidermidis: a possible role in the pustules of rosacea. J Am Acad Dermatol 2011; 64:49.
  8. Dahl MV, Ross AJ, Schlievert PM. Temperature regulates bacterial protein production: possible role in rosacea. J Am Acad Dermatol 2004; 50:266.
  9. Fernandez-Obregon A, Patton DL. The role of Chlamydia pneumoniae in the etiology of acne rosacea: response to the use of oral azithromycin. Cutis 2007; 79:163.
  10. Parodi A, Paolino S, Greco A, et al. Small intestinal bacterial overgrowth in rosacea: clinical effectiveness of its eradication. Clin Gastroenterol Hepatol 2008; 6:759.
  11. Crawford GH, Pelle MT, James WD. Rosacea: I. Etiology, pathogenesis, and subtype classification. J Am Acad Dermatol 2004; 51:327.
  12. Bae YI, Yun SJ, Lee JB, et al. Clinical evaluation of 168 korean patients with rosacea: the sun exposure correlates with the erythematotelangiectatic subtype. Ann Dermatol 2009; 21:243.
  13. Guzman-Sanchez DA, Ishiuji Y, Patel T, et al. Enhanced skin blood flow and sensitivity to noxious heat stimuli in papulopustular rosacea. J Am Acad Dermatol 2007; 57:800.
  14. Spoendlin J, Voegel JJ, Jick SS, Meier CR. Migraine, triptans, and the risk of developing rosacea: a population-based study within the United Kingdom. J Am Acad Dermatol 2013; 69:399.
  15. Abram K, Silm H, Maaroos HI, Oona M. Risk factors associated with rosacea. J Eur Acad Dermatol Venereol 2010; 24:565.
  1. Problems with your immune system
  2. A reaction to microorganisms
  3. Sun exposure
  4. Inappropriate blood vessel function
  5. Genetics