Possible pregnenolone side effects
Overstimulation and insomnia -- low doses could be helpful for sleep when taken in the morning. For occasional sleepless nights, consider Good Night Rx.
Irritability, anger or anxiety -- low doses could actually ease a person into a relaxed feeling, while higher amounts may lead to irritability.
Acne
Headaches
Possible scalp hair loss if used daily for prolonged periods. Pregnenolone converts into DHEA, which in turn converts into testosterone and possibly on to DHT. Pregnenolone can also be converted into progesterone.
Irregularities of heart rhythm, HEART PALPITATIONS, even on as low a dose as 10 mg
Unknown effects on the thyroid gland or other organs and tissues.

From the closing of the article:

Because cancers of the breast, uterus, ovaries, and prostate may grow faster in the presence of sex hormones derived from pregnenolone,54-59 it’s important to collaborate with your health care provider if you have any such conditions, to be sure that supplementation is right for you.

aricept!!!!!