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Limited evidenceWeight management

Forskolin (Coleus)

Forskolin's fat-burner reputation rests on two small 12-week trials from 2005 - and neither actually produced weight loss. One showed a body-composition shift in men without weight change; the other found nothing in women. It is not a proven weight-loss supplement.

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What the science says

  • Changed body composition in men without causing weight loss Limited evidence

    Thirty overweight and obese men took 250 mg of a 10% forskolin extract twice daily or placebo for 12 weeks. Body fat percentage and DXA fat mass fell significantly versus placebo, bone mass changed, free testosterone rose, and lean body mass showed only a trend (p = 0.097). With 15 men per group and no significant weight loss, this is a hypothesis-generating result, not proof of a fat-loss effect.

  • No effect in women Limited evidence

    Twenty-three mildly overweight women took the same product and dose for 12 weeks. There were no significant differences in fat mass, fat-free mass or body fat percentage; Coleus only tended to blunt weight gain (-0.7 vs +1.0 kg, p = 0.10). The authors concluded it does not promote weight loss, and no clinically significant changes appeared in blood lipids, liver and muscle enzymes, thyroid hormones, heart rate or blood pressure.

  • Testosterone booster Limited evidence

    The free-testosterone increase seen in a single 15-man trial has never been replicated, and no trial has linked forskolin to strength, performance or lean-mass gains in trained people.

  • Other uses (eye pressure, bronchodilation) Limited evidence

    Forskolin raises intracellular cAMP and has been investigated as an eye drop for intraocular pressure and by inhalation for bronchodilation. Those are entirely different routes and formulations and tell you nothing about oral capsules for fat loss.

Dosage & safety

Studied dose250 mg of a 10% Coleus forskohlii extract (about 25 mg forskolin) twice daily - the exact dose used in both 2005 trials. No evidence supports higher doses.
SafetyReported effects include loose stools and increased bowel movements. Forskolin is a vasodilator that increases cardiac cAMP signaling, so it can lower blood pressure and increase heart rate; avoid combining with antihypertensives and nitrates without medical supervision. It may increase bleeding risk with anticoagulants and antiplatelet drugs - stop at least two weeks before surgery. It increases gastric acid secretion, so avoid with active peptic ulcer, and it is contraindicated in polycystic kidney disease. Avoid in pregnancy and breastfeeding.

How to take it

TimingTwice daily, matching the dosing in both trials.
With food?Either way; with food if loose stools are a problem.
Worth knowingBuy on forskolin content, not extract weight — 250 mg of a 10% extract is only about 25 mg of the active compound.

Interactions

With medications

  • antihypertensive medication and nitrates

    forskolin is a vasodilator and can add to blood-pressure lowering while raising heart rate do not combine without medical supervision

  • warfarin, DOACs and antiplatelet drugs

    may increase bleeding risk avoid the combination, and stop forskolin at least two weeks before surgery

  • proton pump inhibitors and H2 blockers

    forskolin increases gastric acid secretion, working against acid suppression avoid if you are being treated for ulcer or reflux

With other supplements

  • fish oil, ginkgo, garlic and other bleeding-risk supplements

    additive antiplatelet effect do not stack them, especially before surgery

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does forskolin work for weight loss?

No — forskolin is not a proven weight-loss supplement. Its reputation rests on two small 12-week trials from 2005, and neither produced weight loss: one showed a body-composition shift in thirty men, the other found nothing in women.

Does forskolin boost testosterone?

The evidence is limited to a free-testosterone increase in a single small forskolin trial that has never been replicated. No trial has linked forskolin to strength, performance or lean-mass gains.

How much forskolin should I take?

Both trials used 250 mg of a 10% Coleus forskohlii extract twice daily, which is about 25 mg of forskolin per dose; no evidence supports higher doses. Buy on forskolin content, not extract weight.

What are the side effects of forskolin?

Forskolin can cause loose stools, lower blood pressure and raise heart rate, and it may increase bleeding risk with anticoagulants. Avoid combining it with blood pressure drugs or nitrates without medical supervision, and stop it at least two weeks before surgery.

Scientific references

Where to buy

Nature's Craft, Forskolin, 60 Capsules (250 mg per Capsule)

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