Forskolin (Coleus forskohlii) benefits: what the research does and doesn't show

The evidence doesn't support forskolin, at the doses studied, as a reliable weight-loss aid — the two small human trials on body composition found opposite results in men and women. Its reputation as a fat burner came mostly from TV weight-loss marketing, not from a body of consistent trial data, and its other researched uses, on the eye and the heart, come from completely different, non-oral forms of the compound.

What the evidence doesn't support

It doesn't support forskolin capsules as a dependable way to lose body fat or body weight. Only two placebo-controlled human trials on body composition exist, using the identical extract and dose, and they didn't agree with each other — one found favorable changes in men, the other found none in women (PMID 16129715, PMID 18500958). Two independent reviews that looked across the broader category of weight-loss and "fat burner" supplements both grouped forskolin with ingredients whose evidence is thin or insufficient, not with the small number that reviewers consider well supported (PMID 27053066, PMID 21951331). It also doesn't support the oral capsule as a treatment for elevated eye pressure or a heart condition — the research on those outcomes used a completely different form of forskolin, applied a completely different way, covered below.

What the trials found

A 2005 randomised, double-blind, placebo-controlled trial gave 30 overweight or obese men either 250 mg of a 10%-standardized forskolin extract twice a day (500 mg of extract, about 50 mg of forskolin itself, per day) or a placebo, for 12 weeks. The forskolin group had a significantly greater decrease in body fat percentage and fat mass, measured by DXA scan, than the placebo group, and a significantly greater increase in bone mass. Lean body mass showed a trend toward increase that didn't reach statistical significance (p=0.097). Free testosterone rose significantly more in the forskolin group than placebo; total testosterone changed by 16.8% on average in the forskolin group versus a 1.1% decline in the placebo group, a difference the study didn't find to be statistically significant. The same trial measured blood pressure and metabolic rate, but the published abstract doesn't report specific results for either (PMID 16129715).

A separate 2005 trial, also randomised, double-blind and placebo-controlled, gave the identical extract and dose to mildly overweight women for the same 12 weeks. This time, there were no significant differences between the forskolin and placebo groups in body mass, fat mass, fat-free mass, or body fat percentage. The forskolin group did tend to gain less body mass over the study than the placebo group, and reported less hunger and fullness — subjective measures, not body-composition outcomes. Bloodwork covering lipids, liver and muscle enzymes, electrolytes, blood cell counts and hormones showed no clinically significant differences from placebo, and the study's own conclusion was that forskolin didn't appear to promote weight loss, though it might help limit weight gain (PMID 18500958).

Two broader reviews add context rather than new trial data. A 2016 review of newer weight-loss dietary supplements — covering forskolin alongside about ten others, including Garcinia cambogia and bitter orange — concluded the evidence for this whole category was insufficient to recommend safe use for weight management (PMID 27053066). A 2011 review specifically of "fat burner" supplements singled out caffeine and green tea as the only two with data actually backing their fat-metabolism claims, placing forskolin among several others described as showing "some promise" but lacking the evidence to back it up (PMID 21951331).

Outside of weight, forskolin's research trail runs through the eye. A 1983 study applied a 1% forskolin suspension directly to the eyes of rabbits, monkeys, and human volunteers who did not have glaucoma or any other eye disease. In the human volunteers, a single drop significantly lowered intraocular pressure within an hour, peaked at two hours, and stayed lower for at least five hours (PMID 6132271). A 2012 review describes the same mechanism — forskolin activating an enzyme in the eye's ciliary tissue that reduces fluid production — and notes forskolin became the first plant-derived compound approved as a pharmaceutical product in India, in 2006, specifically in that topical form (PMID 23023353). None of this involved swallowing a capsule, and none of it was tested in people who actually have glaucoma.

On the heart, we found no trial testing oral forskolin extract for a heart-health outcome in people at all. What exists instead is a mechanistic note: because natural forskolin doesn't dissolve well in water, researchers created a separate, modified, water-soluble version of the molecule and studied that different compound for cardiovascular use — not the extract sold in a supplement capsule (PMID 20178070).

Questions people ask

Does forskolin help with weight loss?

The two trials that exist disagree: one found favorable body-composition changes in men, the other found no significant change in women using the identical extract and dose. Two broader reviews of weight-loss supplements both described the evidence for forskolin as thin. That's not a basis for expecting reliable weight loss from it.

Does forskolin increase testosterone?

One small trial in 30 overweight or obese men found a significant increase in free testosterone with forskolin versus placebo over 12 weeks, though the change in total testosterone wasn't statistically significant. That's a single trial in one population (overweight/obese men), not replicated elsewhere in the research we reviewed, and it says nothing about people outside that population.

Is forskolin good for the heart?

No trial we found tested the oral extract for a heart-health outcome in people. A separate, chemically modified, water-soluble version of forskolin has been researched for cardiovascular use — a different compound, not the plant extract in a supplement capsule.

Does forskolin help with eye pressure or glaucoma?

A single dose of forskolin applied as eye drops lowered eye pressure for several hours in healthy volunteers without glaucoma. That's a topical liquid placed directly on the eye, not a capsule that's swallowed, and it hasn't been tested in people who actually have glaucoma — so it doesn't tell you anything about what a forskolin supplement capsule does to eye pressure.

Why was forskolin so heavily marketed for weight loss?

It was promoted extensively in television weight-loss segments as a fast-acting fat burner. The marketing ran well ahead of the science: only two small human trials on body composition exist, they used the same extract and dose, and they reached opposite conclusions.

When to talk to a doctor

A supplement is not a treatment for obesity, low testosterone, elevated eye pressure, glaucoma, or a heart condition, and nothing in the research above supports using forskolin as a substitute for medical evaluation or treatment of any of those. If you're managing your weight, your testosterone, your eye pressure or a heart condition, that's a conversation for a doctor — and if you take a prescription medication, ask a doctor before adding forskolin, since it hasn't been tested in combination with most medications.