Causes
Cradle cap is not caused by a bacterial infection, allergy, not from poor hygiene. Cradle cap is also not contagious. Doctors do not agree on what causes cradle cap, but the two most common hypotheses include fungal infection and overactive sebaceous glands. Cradle cap is an inflammatory condition.
In many cases, what is commonly called cradle cap is actually a fungal infection. This infection may be related to antibiotics given to the mother just before the infant's birth, or the infection could be related to antibiotics routinely given to infants during the first week of life. Antibiotics kill both harmful bacteria as well as the helpful bacteria that prevent the growth of yeast, which is why people who are prone to fungal infections will often discover a fungal infection after taking a round of antibiotics . In infants, the fungus is mostly likely to appear on the scalp (cradle cap), diaper area (fungal diaper rash, jock itch), ear (fungal ear infection, or an ear infection that does not respond to antibiotics),or in the mouth (thrush).
Another common cause of cradle cap appears to be a common manifestation of biotin insufficiency. This may be due, in part, to the influence of biotin on fatty acid biosynthesis. Possibly it has to do with overactive sebaceous glands in the skin of newborn babies, due to the mother's hormones still in the baby's circulation. The glands release a greasy substance that makes old skin cells attach to the scalp instead of falling off as they dry. There may be a relationship with skin yeasts (Pityrosporum ovale, newly renamed Malassezia furfur). Seborrheic dermatitis is the adult version of cradle cap.
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