Combination of
Erythromycin Macrolide antibiotic
Tretinoin Retinoid
Clinical data
Routes of

The drug combination erythromycin/tretinoin (trade name Isotrexin) is a topical gel with active ingredients erythromycin 2% w/w and tretinoin 0.05% w/w for the treatment of acne.

Tretinoin is a type of vitamin A. It reduces the production of sebum. (Sebum is a sticky oil-like substance which is produced from the sebaceous gland.)

Erythromycin is an antibiotic.

Acne is caused by blockage of the pores. This leads to an accumulation of the skins natural oils and bacteria (Propionibacterium acnes) in the skin (which feed on the oils and keratin) which further inflame the gland causing acne. The active ingredients reduce the changes the bacteria causes to try to stop the acne.


  • Avoid direct sunlight & tanning machines (i.e. sunbeds) as it can induce sensitivity.
  • Do not use near eyes or mouth.
  • Wash hands after use.
  • Do not use during pregnancy.
  • Do not use during breast feeding.
  • Do not use if you are sensitive to either of the listed ingredients.
  • If skin starts to burn when wearing wash off & do not use until have spoken to your GP.
  • If the skin starts to dry out, stop or reduce your applications.

External links

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