Are photosensitizers for internal use?

Are photosensitizers for internal use? Or can they only be used externally — for example, can they be used inside the vagina or inside the mouth?

Photosensitizers can be used both externally and internally (e.g., oral administration, intravenous injection). They can therefore also be used for local treatment inside the vagina or inside the mouth.

The routes of administration for photosensitizers are very flexible and mainly depend on the treatment site and purpose. Common ones include:

l Topical external use: commonly used for skin diseases, oral mucosal diseases, etc.

l Oral administration: e.g., oral medications for treating vitiligo, or nano-formulations for intestinal diseases.

l Intravenous / local injection: used for the treatment of deep-seated or specific sites such as tumors.

l Intracavitary administration: e.g., gel formulations used inside the vagina, or suppositories used rectally.

Both of the sites you mentioned have mature applications:

Applications inside the mouth

In dentistry, photodynamic therapy (PDT) is a minimally invasive method for treating oral leukoplakia, oral precancerous lesions, periodontal disease, and so on. The physician applies the photosensitizer (such as aminolevulinic acid, i.e., ALA) onto the lesion mucosa as a coating or wet compress, waits several hours for it to be absorbed by the abnormal cells, and then activates it by irradiation with a laser of a specific wavelength.

Applications inside the vagina

In gynecology, this is mainly used to treat HPV infection, cervical lesions, condyloma acuminatum (genital warts), etc. The physician prepares a photosensitizer gel (such as 20% "Aila" (ALA) thermosensitive gel), applies it to the surface of the patient's cervix, vagina, or vulva, waits about 4 hours for the drug to fully penetrate, and then performs the light irradiation.

In short, photosensitizers are by no means limited to external use — they have mature medical applications in internal body sites such as the mouth and the vagina. However, all of these are strictly medical procedures that must be carried out by or under the guidance of a professional physician. You must absolutely never purchase and use them on your own.