Scullcap is a member of the mint family and a native of North America, where it thrives in moist woodlands. Common names for it include helmetflower, hoodwort, and mad-dog weed (from its introduction into American medicine in 1773).
A physician in New Jersey, Dr. Lawrence Van Derveer, claimed it was useful in treating hydrophobia (an old term for rabies).
Although he was said to have lost only three patients out of a large number he treated, other doctors were, understandably, less successful in curing rabies with scullcap. (To this date, prompt administration of the rabies vaccine is the only effective treatment.)
A number of related species grow in Asia. At least one of these, S. baicalensis Georgi, has been used in Europe and China (where it is known as huang qin). But although these plants appear to have some active ingredients in common, the ways they are used is very different.
The aboveground parts of scullcap collected during the blooming season (August and September) are dried and used as herb. It is, however, the dried root of huang qin that is used medicinally in China.
Scutellaria species contain a number of flavonoid glycosides, including scutellarein, isoscutellarein, wogonin, and baicalin. S. baicalensis root contains baicalein, baicalin, wogonin, and beta-sitosterol.
Scullcap has traditionally been used in combination with valerian as a mild sedative for anxiety. It has also been used in patent medicines for “female problems.”
Tests of scullcap extract did not reveal that it stops muscle spasms or that it slows down animals or makes them sleep. Most studies did not indicate any effect on heart rate or blood pressure, although Japanese scientists found that an extract of S. baicalensis reduced blood pressure in dogs.
The scientific research does not support the use of scullcap as a tranquilizing herb or for the treatment of hormonal problems.
Chinese research has shown, however, that extracts of S. baicalensis root are active against a range of bacteria and that the herb is an effective antiviral agent to treat the flu. It is prescribed for acute tonsillitis and strep throat.
A constituent, baicalin, inhibits HIV-1.
Baicalin also appears to inhibit tumor growth and has strong anti-inflammatory activity.
Both baicalin and baicalein are powerful antioxidants, protecting red blood cells from free radical damage better than vitamin E can. They both show some promise in preventing the oxidation of blood fats, although baicalein appears to be more active here.
No standard dose of scullcap has been established in the United States or Europe. In China, baicalin is available in 250-mg tablets.
The dose prescribed for viral hepatitis is two tablets three times a day.
The herb is said to be dangerous in overdose.
In the U.S. market, it is difficult to determine if the scullcap you have purchased actually contains S. lateriflora.
Apparently adulteration is common, and one plant Teucrium, often substituted for scullcap appears to be harmful to the liver.
Swallowing scullcap at normal doses does not generally result in serious side effects.
Injection of S. baicalensis extracts, however, can cause fever, muscle pain, and lowered leukocyte count.
In several instances, people taking scullcap have experienced liver damage. Varro E. Tyler hypothesizes that this may be due to adulteration with another herb. The danger of liver toxicity should, however, discourage casual use of the herb.
The only interactions reported are from animal studies. The anticancer agents cyclophosphamide and 5-fluorouracil were less toxic and more potent when given together with a scullcap extract.