Skullcap: sounds like the name of a heavy metal band or something you might dress up as for Halloween. But fear not; considering its beneficial bioactive properties this herb is anything but scary. The name “skullcap” comes from the appearance of the outer portion of this plant’s eye-catching purple/blue flowers. It thrives in woodlands and along stream banks and it flowers from May through September. The leaves are the part harvested for medicinal purposes and they’re usually concentrated in powdered form or as a liquid extract. (It can be used as a tea or tincture as well.) 

There are two forms of skullcap employed for medicinal reasons: American skullcap (Scutellaria lateriflora) and Chinese skullcap (Scutellaria baicalensis). They are not interchangeable. This brief exploration is focused on American skullcap. American skullcap is native to North America but is now widely cultivated elsewhere as well. It has been used for over two centuries as a mild relaxant for anxiety nervous tension and convulsions which underlies its inclusion in herbal formulas designed to support relaxation and calming. Other research suggests that plants of the Scutellaria genus may exhibit antioxidant antibacterial and antiviral capacity. Legend has it skullcap was sometimes used as a remedy for rabies which garnered it the nickname “mad-dog skullcap.” 

The anti-seizure effects of American skullcap have been confirmed in animal models. The stress and anxiety reducing potential has been demonstrated in animal and human trials. The flavonoid baicalin and its derivative aglycone baicalein are capable of binding to the benzodiazepine sites of GABA receptors and acting as GABA agonists which is likely what underlies skullcap’s anxiolytic effects. In healthy adults with relatively low levels of anxiety compared to placebo oral administration of skullcap (350 mg T.I.D.) for two weeks resulted in significant decreases in total mood disturbance as measured by the Profile of Mood States. These changes occurred without detrimental effects on cognition or physical energy levels which may be of benefit to individuals who experience adverse side-effects in these areas when using prescription drugs or other compounds for anxiety or nervous tension.

In addition to helping promote calm extracts of American skullcap are believed to be generally neuroprotective. In vitro studies of mouse brain tissue indicate skullcap is a potent antioxidant and protects against DNA damage induced by oxidative stress. Alcohol and water-based skullcap extracts were effective scavengers of DPPH radicals and the alcohol-based extract reduced chemically induced lipid peroxidation in the brain.

An interesting property of skullcap unrelated to its effects on mood and psychology is the potential for some of its phenolic constituents to inhibit intestinal alpha-glucosidase sucrase and maltase at least in rats. 

Skullcap is contraindicated during pregnancy and breastfeeding and caution is warranted when adding skullcap to the regimen of individuals taking anticonvulsants (such as phenytoin and valproic acid) barbiturates benzodiazepines prescription drugs for insomnia tricyclic antidepressants and other herbs with sedating effects as valerian kava and catnip. People should avoid consuming more than moderate amounts of alcohol while taking skullcap due to possible additive effects.

Another concern regarding the use of skullcap is potential hepatotoxicity. According to the U.S. National Institutes of Health (NIH) “Skullcap has been implicated in rare instances of clinically apparent liver injury although in most cases multiple herbal medications were being taken and the role of skullcap in the hepatic damage was unclear. Furthermore in some instances phytochemical analysis has identified significant adulterants (germander) or mislabelling in cases of suspected skullcap hepatotoxicity.” One case involving an herbal sleep aid that contained skullcap and valerian was evidenced by jaundice with elevated ALT AST alkaline phosphatase and bilirubin. The jaundice resolved within a month of discontinuing use of the product and all affected biomarkers resolved completely within three months with no evidence of permanent damage.