Side effects
After an intake of 1.5 mg levonorgestrel in clinical trials, very common side effects (reported by 10% or more) included: hives, dizziness, hair loss, headache, nausea, abdominal pain, uterine pain, delayed menstruation, heavy menstruation, uterine bleeding, and fatigue; common side effects (reported by 1% to 10%) included diarrhea, vomiting, and painful menstruation; these side effects usually disappeared within 48 hours. However, the long term side effects common with oral contraceptives such as arterial disease are lower with levonorgestrel than in combination pills.Levonorgestrel as a contraceptive intrauterine device is associated with a higher risk of breast cancer than with non-use. Overdose
Overdose of levonorgestrel as an emergency contraceptive has not been described. Nausea and vomiting might be expected. Interactions
If taken together with drugs that induce the CYP3A4 cytochrome P450 liver enzyme, levonorgestrel may be metabolized faster and may have lower effectiveness. These include, but are not limited to barbiturates, bosentan, carbamazepine, felbamate, griseofulvin, oxcarbazepine, phenytoin, rifampin, St. Johns wort and topiramate. Pharmacology
Pharmacodynamics
Levonorgestrel is a progestogen with weak androgenic activity. It has no other important hormonal activity, including no estrogenic, glucocorticoid, or antimineralocorticoid activity. The lack of significant mineralocorticoid or antimineralocorticoid activity with levonorgestrel is in spite of it having relatively high affinity for the mineralocorticoid receptor, which is as much as 75% of that of aldosterone. Progestogenic activity
Levonorgestrel is a progestogen; that is, an agonist of the progesterone receptor (PR), the main biological target of the progestogen sex hormone progesterone. It has effects similar to those of the hormone progesterone.
Keratosis follicularis may refer to:

Dariers disease
Focal palmoplantar keratoderma with oral mucosal hyperkeratosisSee also:

Isolated dyskeratosis follicularis
Keratosis follicularis spinulosa decalvans