Oral formulations and method of formulating photosensitive agents for oral administration during photodynamic therapy (PDT) and Antimicrobial photodynamic therapy (APDT) treatment are presented. The oral formulated photosensitizers show increased solubility and permeability, thus improving the bioavailability of photosensitizers at the treatment site. An orally administered photosensitizer is suitably formulated for mucosal adhesion and absorption via gastrointestinal mucosal membranes. Oral formulation provided herein use lipids and known proteins as carriers for photosensitizers by oral route. Carriers for encapsulating preselected photosensitizers include conventional liposomes, pegylated liposomes, nanoemulsions, nanocrystrals, nanoparticles, fatty emulsions, lipidic formulations, hydrosols, SMEDDS, Alpha-Feto protein (AFP), and Bovine-Serum-Albumin (BSA), fatty emulsions, hot-melt-extrudates and nanoparticles. The oral formulation, in case of a hydrophobic photosensitizer in the present invention, is stabilized using suitable surfactants/solubilizers thus preventing aggregation of the drug in the stomach and until it is absorbed in the duodenum and the small intestine. Oral formulations can be administered in the form of liquid, capsule, tablet, powder, paste or gel. Formulated drugs can be administered orally as one single dose or in multiple doses before administering PDT. In one embodiment Temoporfin (m-THPC) is used as a photosensitizer in the oral formulations. Temoporfin like many hydrophobic photosensitizers are especially suitable to be administered orally because there is no known enzyme system in the mammalian body which can metabolize Temoporfin or similar photosensitizers. Temoporfin can reach the blood system unchanged and fully active after absorption of the formulation in the gastrointestinal tract.