Inclusion Criteria:

- At least 4-10 clinically assessed actinic keratosis grade I to II (according to Olsen
et al, 1991) in the face/forehead and/or on the bald scalp

- The diameter of each AK target lesion is not less than 0.5 cm and not greater than
1.5 cm

- The target lesions must be located in overall 2 treatment areas with a size of 25 cm2
per treatment area

Exclusion Criteria:

- Have evidence of clinically significant or unstable medical conditions such as:

- metastatic tumor or tumor with high probability of metastatic spread

- heart failure (NYHA class III or higher)

- immunosuppressive disorder (e.g. HIV)

- hematologic, hepatic, renal, neurologic or endocrine disorder.

- collagen-vascular disorder (e.g. cerebrovascular disorder or other bleedings).

- gastrointestinal disorder (e.g. active ulcera or history of recurrent peptic
ulcera or hemorrhage)

- Suffer from paresthesia in the treatment areas

- Show Cornu cutaneum of the skin and/or hypertrophic AK lesions in the treatment areas