Where to apply the ointment
“For external use only” is a note mentioned on the label of certain pharmaceutical formulas. This is notably the case for Zincofax and Ihle’s Paste (25% zinc oxide). Keep in mind that the “For external use only” note simply means that you cannot eat the product!
On a more serious note, most creams and ointments for anal application can (and very often must) be inserted into the anal canal. As such, treatments for anal fissure or hemorrhoids, or to be used following anal surgery, must be inserted into the anal canal.
Protective creams (such as Ihle’s Paste) must be inserted into the anal canal, which does not mean they cannot be applied externally as well.
For the treatment of skin conditions (perianal dermatitis), external application is sufficient (although internal application is certainly not detrimental).
Keep in mind that the lower half of the anal canal is made up of skin (also called the anoderm). This entire portion is considered external and is what a product refers to when it bears the “For external use only” note. The anoderm is 2 to 4 centimetres long.
In the case of anal fissure, treatment aims at relaxing the internal sphincter and the only way to reach it with an ointment or a cream is to apply it in the anal canal. To recommend applying it externally is therefore totally ineffective.
For hemorrhoidal conditions, combined application (internal and external) is recommended.
For anal pain, a sitz bath is very effective and an analgesic ointment (Xylocaine base) can be applied using one’s finger rather than a cannula.
In all of these cases, application with a finger or dilator is desirable. This is primarily because the use of perforated cannulas pushes the cream or ointment into the rectum, which is not desirable, except in certain special cases.
If treatment is to be applied in the rectum (i.e.: higher than the anal canal), the use of suppositories or foam is preferred.