Inclusion Exclusion
IGA 3-4 (severe papulo-pustular or conglobate acne) Isotretinoin or tetracyclines systemic treatment within last 12 months
Partial/absent response to previous acne treatments Topical retinoid treatment within last 6 months
Ineligibility to standard dose of retinoids Use of photosensitivity-inducing drugs
Refusing standard dosage therapy with isotretinoin due to risk of collateral effects Use of corticosteroids within last 6 months
Anamnestic discontinuation of standard dosage therapy with systemic retinoids due to unsustainable side-effects Pregnancy or breast-feeding
No clearance with combined tetracycline and topical therapy