Coleus forskohlii is a perennial bush that is native to India. It has aromatic green leaves that grow off erect stems, and can reach heights of 2 feet. This plant grows in well-drained soil located either in partial shade or full sun, and can be found in the foothills of the Himalayas. It also grows in parts of Eastern Africa, Sri Lanka, and Nepal.
Coleus was traditionally used as a folk medicine in India. It’s most popular uses were for digestive complaints such as gas and bloating. In the 1970’s, a group of scientists in Germany isolated the constituent forskolin from the root. Since then, coleus has gained popularity for uses attributed to the activity of its primary constituent, forskolin. Most of the research that has been done on coleus is actually on this chemical constituent, and not the activity of the whole plant.
Coleus contains two main constituents, the volatile oils and forskolin - a diterpene. The volatile oils are located high in the leaves and provide coleus with its carminative action. These oils are useful for complaints of the digestive system. The carminative action can relieve gas and bloating, as well as ease abdominal discomfort. Other carminative herbs include fennel, cinnamon, anise, and ginger.
Forskolin, which is found in the root, exerts its action by activating a cell-signaling molecule, adenylate cyclase. An important cell-signaling molecule, adenylate cyclase increases cyclic AMP, which is responsible for inducing various biochemical reactions in the body. The secretion of thyroid hormones and insulin, vasodilation of blood vessels and airways, and the regulation of pressure in the eye are all mediated by cyclic AMP (cAMP).
The leaf and the root of coleus can be used medicinally. Use of the leaf dates back centuries as a common remedy for digestive complaints. Today, the root is primarily used for its forskolin content. Most of the research conducted on this plant, has focused on use of the root; specifically on the isolated constituent forskolin.
Coleus can be used as a treatment for various disorders of the cardiovascular system. Coleus may lower blood pressure by causing a vasodilation of blood vessels.  By reducing the workload on the heart, and increasing it efficiency, coleus is also helpful for congestive heart failure.  Coleus may also provide a legitimate treatment for atherosclerosis, due to its ability to inhibit platelet aggregation via increases in cyclic AMP. 
Coleus is an effective treatment for glaucoma, more specifically, open angle glaucoma that results in an increase in intraocular pressure. Coleus can be taken internally or applied topically for this condition. By increasing cAMP it causes a reduction in the intra-ocular pressure.  It is believed that by doing this, inflow of aqueous humor from the back of the eye to the anterior chamber of the eye is reduced.
Coleus is also useful in the treatment of asthma. Like glaucoma, coleus is thought to provide therapeutic benefit in asthma by the same mechanism of increasing cyclic AMP. In study, coleus has been shown to dilate the bronchioles, which the opposite effect of an asthma attack.  Coleus also causes a decrease in histamine and leukotrienes release, two of the main cell signaling molecules responsible for the symptoms of an asthma attack; as well as allergies. 
Coleus can be used as a medicinal remedy is several different delivery forms. Capsules can be taken in standardized doses. The most common recommendations are 250 milligrams (standardized to 1% forskolin) taken 1-3 times a day, or 50 mg (standardized to 18% forskolin) taken 1-2 times a day. 
The leaves can be administered as a tea or infusion, with 3 grams of herb infused in 1 cup of water, drank twice daily. The root may also be decocted (boiled), with 15 grams of root per 2 cups of water, drank in 1/4 cup increments, 4 times daily.
There are no reported toxicities concerning the use of coleus when administered at the recommended dosages.
Use in women who are pregnant or lactating is contraindicated due to the lack of information about use in these particular populations.
Individuals who are currently taking medications to lower blood pressure should not take coleus without first consulting with their physician. There is a slight potential for additive effects, resulting in substantial decreases to blood pressure.
Individuals who have a bleeding disorder, or who are taking anti-coagulation or anti-platelet medications, should first consult with a physician before beginning coleus supplementation. This includes people with bleeding gastric ulcers, hemophilia, as well as those taking prescription medications.
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