This is a single center, double-blind (patient and investigator), randomized, placebo-controlled study with a split-lesion design, in which selected keloids will receive three consecutive treatments of a) bleomycin and b) placebo (saline (NaCl 0,9%)), administered with an electronic pneumatic jet injector.

This is a single center, double-blind (patient and investigator), randomized, placebo-controlled study with a split-lesion design.All study procedures will be performed at the Department of Dermatology, Erasmus MC Medical Center in patients referred for scar treatment to our outpatient clinic.

Clinical photos will be obtained after signing the informed consent form by patient and investigator. Study visits and clinical assessments will be scheduled at baseline, 4 weeks, 8 weeks, and 12 weeks. Measurements include clinical photography, scar volume measured by 3D-camera, POSAS questionnaire, laser speckle contrast imaging to visualize keloid scar vascularization, measurement of residue formation on the skin, and a treatment related questionnaire. The keloid will be divided into two treatment areas, and randomly assigned to three consecutive treatments of: a) bleomycin and b) placebo (saline (NaCl 0,9%)), administered with an electronic pneumatic jet injector.

Inclusion Criteria:

1. Subject has provided written informed consent;
2. Subject is ≥ 18 years of age at time of screening;
3. Subject has at least one keloid scar of ≥ 4 cm in length, or two separate keloids with a length of ≥2cm, with a minimum > 1.0 cm apart in the same anatomical region.
4. Subject is willing to fill in questionnaires and take photos using an e-diary application on their phone.

Exclusion Criteria:

1. Known hypersensitivity to any component of the test materials;
2. Pregnant or breast-feeding women (pregnancy test prior to treatment);
3. Previous bleomycin treatment of the keloid within the last 12 weeks prior to screening.
4. Non-response to previous bleomycin treatments of the keloid.
5. Any medical or psychiatric condition which, in the investigator's opinion, would preclude the participant from adhering to the protocol or completing the study per protocol.