For Patients & Caregivers
Bottom Line: Forskolin has not been shown to be an effective cancer therapy in human. More large scale clinical studies are needed to support its other uses.
Forskolin is a root extract of the Indian plant Coleus forskohlii. It is thought to stimulate a cell enzyme called adenylate cyclase, causing higher-than-normal levels of cAMP, a molecule that is responsible for many cellular effects. Some of these effects include the breakdown of fats, dilation of blood vessels and airways, inhibition of blood clotting, and improve of the heart’s function. Recent animal study showed that forskolin can cause tanning when applied directly to the skin without exposure to the sun. It has been proposed to be used in sunless tanning lotion to reduce skin cancer risks. Although these effects have been studied in the laboratory setting, very few clinical trials have been performed to test whether these effects also occur in humans. In a number of studies, forskolin was found to lower pressure in the eye but this effect remains controversial.
- As a bronchodilator to treat asthma
Forskolin may cause cellular changes that stimulate the dilation of airways.
- To treat cancer
Scientific evidence is limited to lab and animals studies. There is no human trial to support this use.
- To increase cardiac output in congestive heart failure
Two clinical trials found positive effects of intravenous forskolin extract in patients with acute heart failure, but overall support for this use is not strong. Oral forms of this herb have not been tested in humans.
- As an eye drop, to reduce intra-ocular pressure in glaucoma
Studies in humans have conflicting results.
- To lower high blood pressure
Forskolin is known to cause cellular changes that lead to blood vessel dilation, which should lower blood pressure, but there is no proof from clinical trials that this effect occurs in humans.
- For weight loss
A small clinical study suggests forskolin may have benefits in obese men.
- For tanning
This has been studied in animals. More studies are needed in humans.
Two clinical trials conducted in Japan used an intravenous forskolin extract to treat patients with acute heart failure, with positive results, but overall there is no strong support for this use. In addition, it is not known whether forskolin taken by mouth will have the same effect as when it is given intravenously.
- Forskolin formulations that are not designed for use in the eye (such as topical creams or extracts meant to be taken by mouth) SHOULD NOT BE PLACED DIRECTLY IN THE EYE.
- Acute poisoning after the consumption of Coleus forskohlii products, possibly from contaminants, have been reported in Europe
- Forskolin preparations should not be used by patients with polycystic kidney disease.
- You are taking medication for high blood pressure such as beta-blockers, vasodilators, ACE inhibitors, or calcium channel blockers (Forskolin may lower your blood pressure even more).
- You are taking warfarin or other blood thinners (Forskolin may have additive effects, increasing the risk of bleeding or bruising).
For Healthcare Professionals
Forskolin is a diterpene derived from the root of Coleus forskohlii. It is used for a variety of conditions, including cancer, obesity, glaucoma, asthma, and heart failure. Forskolin was shown in animal studies to promote the activation of adenylate cyclase and increase intracellular concentrations of cyclic adenosine monophosphate (cAMP) (1). Small clinical trials did suggest forskolin can benefit obese men in weight management (2). Forskolin eye drops may reduce intra-ocular pressure (3) and oral forskolin capsules help reduce asthma attacks (4). When administered intravenously or inhaled, Forskolin has bronchodilation effect (5)(6). Other studies demonstrated forskolin to have cardiovascular benefits due to its inotropic (7), antiinflammatory (8) and antiplatelet properties (9). One clinical study found intraarterial forskolin daropate to be an effective treatment for cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage (10). Treatment of uropathogenic E.coli infected mice with forskolin resulted in reduced number of bacteria via cyclic AMP-regulated exocytosis (11). The anticancer effects of forskolin and its derivatives have also been studied in vitro (1) and in animals (12). Forskolin, when applied on the skin of mice, can stimulate the production of melanin in the absence of ultraviolet light (12). It has been proposed for use in sunless tanning lotions to reduce the risk of skin cancer by decreasing exposure to sun. In an in vitro study, an extract of forskolin was found to significantly reduce viral production in human lymphoid CEM-GFP cells infected with human immunodeficiency virus (HIV-1NL4)(14). These effects have yet to be confirmed in human studies. Patients using anticoagulants and antihypertensive medications should use forskolin with caution. Cases of acute poisoning after the consumption of Coleus forskohlii products, possibly from contaminants, have been reported in Europe (15).
Forskolin activates adenylate cyclase through direct stimulation of enzyme and by modulating enzyme activities. These lead to increase in intracellular concentrations of cyclic adenosine monophosphate (cAMP) (1). This may explain the bronchodilation (4)(5)(6), inotropic (7), vasodilatory (16) and antiplatelet (11) effects of Forskolin. Forskolin has also been reported to increase cellular acetylcholinesterase and protect neuronal cells from organophosphate toxicity (17). Forskolin is thought to reduce body fat and has been studied as a weight loss agent (2). In vitro and animals studies have shown forskolin and its derivative can inhibit cell proliferation, and induce cell cycle arrest and apoptosis in human gastric cancer cells (18)(19). Forskolin was also found to inhibit melanoma cell-induced platelet aggregation and reduce lung metastasis (13). Forskolin upregulates the expression of cytochrome P450 3A (CYP3A) family through the pregnane-X-receptor that regulates the CYP3A genes (20)(21).
Forskolin may have a role in promoting cyst enlargement in patients with polycystic kidney disease. It is therefore recommended that these patients avoid the use of all preparations containing this compound (22).
Anti-hypertensives: Forskolin may have additive hypotensive effect with beta-blockers, vasodilators, calcium channel blockers, etc. (7).
Anticoagulants: Forskolin may cause bleeding due to additive platelet inhibition (9).
Forskolin can induce CYP3A gene expression and can potentially increase the metabolism of drugs that are substrates of related microsomal enzymes (20)(21).
Suzuki S, et al. Intra-arterial colforsin daropate for the treatment of cerebral vasospasm after aneurysmal subarachnoid hemorrhage. Neuroradiology. 2010 Sep;52(9):837-45.
This retrospective study examined the safety and efficacy of an intra-arterial injection of colforsin daropate hydrochloride (CDH), administered to patients with cerebral vasospasm (CV) after aneurysmal subarachnoid hemorrhage (SAH). A consecutive series of 29 patients with angiographically confirmed CV received treatment with intra-arterial CDH (IAC). Angiographic changes in spastic vessels, cerebral circulation time (CCT), and change in clinical status were assessed pre- and post- IAC treatment. Fifty-three IAC procedures were performed in the 29 patients. Angiographic improvement was observed after 100% of the procedures, and clinical improvement was observed in 86% (36/42) of symptomatic cases. At a 3 month follow-up visit, 66% (n=19) had moderate disability on the Glasgow Outcome Scale, demonstrating a good recovery. Notable side effects with IAC treatment included a minor but significant reduction in blood pressure, increased heart rate, and headache. The investigators concluded that IAC treatment was effective and safe for the treatment of CV in patients with SAH, but further study is needed. Limited data are available concerning the efficacy of forskolin.