Shampoo made with the active ingredient ketoconazole is primarily used in anti-fungal applications, treating infections with fungi and yeasts by interfering with the cell membranes of the infecting agents. Fungi cell membranes rely on the substance ergosterol to maintain their membrane walls. Ketoconazole blocks the production of ergosterol, causing the fungal cell membrane to break down and the fungi to die. While effective, some or all of the following side effects may occur after exposure.
In some cases, skin may experience a burning sensation during or after contact with ketoconazole. This may be a temporary, harmless reaction or it may indicate a more severe reaction. The intense and prolonged itching sensation known as pruritus can result from exposure and can cause long-term discomfort in the affected area. In cases where an allergic reaction occurs, contact dermatitis will produce many of the same symptoms and outcomes as pruritus. Eczema, in which the skin becomes inflamed and experiences vesiculation, can be one of the more severe reactions of exposure to ketoconazole.
Changes to Hair
The health of hair can be radically changed by exposure to ketoconazole. Hair may become excessively oily or dry and brittle after use. If used on hair that has been treated (with color or by a perm, for example) and has undergone chemical damage, or on grey hair, sudden and potentially embarrassing discoloration can occur.
In extreme cases, when the scalp and/or the hair are sufficiently damaged by the application of ketoconazole, hair loss can occur. This can be caused by excessive drying and breaking of the hair, rendering the hair so unhealthy that it simply falls out, or it can be due to widespread damage of the follicles within the affected area of the scalp. Recovery from hair loss due to ketoconazole exposure will vary depending on the exact nature of the hair loss.