Skullcap can refer to 2 herbs: American skullcap (Scutellaria lateriflora) and Chinese skullcap (Scutellaria baicalensis). Both forms of skullcap are used to treat different conditions and are not interchangeable.

American skullcap is native to North America, but it is now widely cultivated in Europe and other areas of the world. It has been used for more than 200 years as a mild relaxant and as a therapy for anxiety, nervous tension, and convulsions. Studies show American skullcap has significant antioxidant effects, and may help protect against neurological disorders, such as Alzheimer's disease, Parkinson's disease, anxiety, and depression. There's even some evidence to suggest that American skullcap may inhibit food allergic response. Today, other herbs (such as valerian) are more commonly used, although American skullcap may be combined with other calming herbs in some preparations.

Most of the studies done on skullcap have examined Chinese skullcap. Native to China and parts of Russia, Chinese skullcap has been used in traditional Chinese medicine to treat allergies, infections, inflammation, cancer, and headaches. It may also have antifungal and antiviral effects. Animal studies suggest that Chinese skullcap may help reduce symptoms of diabetes and hypertension (high blood pressure), but scientists don't know if Chinese scullcap has the same effect in humans. In test tubes and animal studies, Chinese skullcap appears to have some cancer-fighting properties. More research is needed to determine any benefit.

American skullcap derives its name from the caplike appearance of the outer whorl of its small blue or purple flowers. It is a slender, heavily-branched plant that grows to a height of 2 to 4 feet and blooms each July. It grows wild in woods and meadows.

Chinese skullcap is related to and resembles American skullcap, but it is a different plant. Its single stems bear a profusion of blue or purple flowers.

American skullcap

The leaves are used for medicinal purposes. These are harvested in June from a 3- to 4-year-old skullcap plant.

Chinese skullcap

The root is used medicinally.

American skullcap is available as a powder or liquid extract.

Chinese skullcap is available as a powder.

Pediatric

Neither American skullcap nor Chinese skullcap is recommended for children.

Adult

Skullcap is available as an encapsulated dried herb, tea, fluid extract, and tincture. Speak to your physician to find the right form and dose for your needs.

Chinese skullcap is often combined with other herbs into a preparation; follow dosing recommendations on the label.

The use of herbs is a time-honored approach to strengthening the body and treating disease. However, herbs can trigger side effects, and can interact with other herbs, supplements, or medications. For these reasons, you should take herbs with care, under the supervision of a health care provider.

American skullcap

• In the past, American skullcap has been contaminated with germander (Teucrium), a group of plants known to cause liver problems. It is important that American skullcap be obtained from a reliable source.
• High doses of the tincture may cause giddiness, stupor, mental confusion, twitching, irregular heartbeat, and seizures.
• American skullcap should not be used during pregnancy and breastfeeding.

Chinese skullcap

• If you have diabetes, DO NOT take Chinese skullcap without your doctor's supervision. Chinese skullcap may lower blood sugar levels, raising the risk of hypoglycemia (low blood sugar).
• Avoid Chinese skullcap if you have stomach or spleen problems.
• Chinese skullcap should not be used during pregnancy or breastfeeding.

If you are being treated with any of the following medications, you should not use either American skullcap or Chinese skullcap without first talking to your health care provider.

Sedatives

Both American skullcap and Chinese skullcap can increase the effect of drugs that have a sedating effect, including:

• Anticonvulsants, such as phenytoin (Dilantin) and valproic acid (Depakote)
• Barbiturates
• Benzodiazepines, such as alprazolam (Xanax) and diazepam (Valium)
• Drugs to treat insomnia, such as zolpidem (Ambien), zaleplon (Sonata), eszopiclone (Lunesta), and ramelteon (Rozerem)
• Tricyclic antidepressants, such as amitriptyline (Elavil)
• Alcohol

The same is true of herbs with a sedating effect, such as valerian, kava, and catnip.

Drugs for Diabetes

Chinese skullcap can lower blood sugar, and could strengthen the effects of drugs taken for diabetes, increasing the risk of hypoglycemia (low blood sugar).

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