- 01Less body fat in one trial is not weight loss
Forskolin's reputation as a fat burner rests mainly on one 12-week trial in 30 men, which reported less body fat on scans rather than weight lost on a scale. A similar trial in women found no real fat loss, and a diet trial found the waist shrank equally on placebo. The same cAMP effect behind the fat-loss theory also lowers blood pressure and slows platelets in lab work, which is why the cautions matter more than the headline.
Coleus forskohlii (also listed as Plectranthus barbatus) is a plant in the mint family from India, Nepal and Thailand whose root has a long history in Ayurvedic medicine. Its active compound, forskolin, raises cAMP (cyclic adenosine monophosphate, a messenger molecule inside cells), which in lab studies helps release stored fat; that is how it became a weight-loss supplement. In people, the evidence is three or four small trials with mixed results: less body fat in one study of 30 men 1, no real fat loss in one study of women 2, and no clinical trials proving its safety and effectiveness for most uses 5.
What is Coleus forskohlii?
Coleus forskohlii is an herb whose roots have long been used in Ayurvedic medicine 57, and the compound that draws interest is forskolin. For the basics, what it is and what it does in your body has its own page. This guide covers what the evidence shows for weight, testosterone, blood sugar and cholesterol, how much studies use, when to take it, side effects and interactions.
Forslean is a branded 10% extract, and it is the extract used in the two best-known body composition trials 12. Other branded extracts differ: a 2026 trial tested one called Forcslim, and its results do not automatically transfer to Forslean 4. You may also see the plant sold as coleus root, makandi, or under the drug name colforsin for a related form 5.
From root to fat cell: the theory behind forskolin
What forskolin is good for: the evidence, graded
Strong means several good randomized trials or a meta-analysis (a study that pools many trials) agree. Moderate means several randomized trials, mostly positive but small or short. Limited means few or small trials, or mixed results. Early means lab, animal or one pilot study only. Not supported means good trials found no benefit. Our guide to how supplements are judged explains why the size and number of trials matter so much here.
| Use | What the research found | Evidence | Source |
|---|---|---|---|
| Body fat in overweight men | 30 men, 12 weeks, 250 mg of 10% extract twice a day: body fat percentage and fat mass fell vs placebo on body scans | Limited | 1 |
| Body fat and weight in women | 23 mildly overweight women, 12 weeks, same extract: no significant change in fat mass or body fat; possibly less weight gain | Limited | 2 |
| Weight with a calorie-cut diet | 30 adults, 12 weeks: waist and hip shrank equally on extract and placebo | Limited | 3 |
| Weight with a different extract (Forcslim) | 60 overweight adults, quasi-randomized: about 1.9 kg more weight loss and 1.8 cm off the waist vs placebo | Limited | 4 |
| Testosterone in men | Free testosterone rose in the 30-man trial; total testosterone change was not significant | Early | 1 |
| Insulin and insulin resistance | Fasting insulin and insulin resistance improved vs placebo in one 30-person diet trial | Early | 3 |
| Blood pressure | Lowers it in lab and animal work; oral trials at supplement amounts saw no change in blood pressure | Early | 524 |
| Asthma attacks | One single-blinded trial of 40 children and adults with asthma on 10 mg of forskolin a day; not compared with the inhalers used today; forskolin is not an asthma treatment | Early | 9 |
Does forskolin help you lose weight?
The answer depends on what you mean by weight. The trial that made forskolin famous, published in 2005, gave 30 overweight or obese men 250 mg of a 10% forskolin extract twice a day, or a placebo, for 12 weeks. On DXA scans (a body composition X-ray), body fat percentage and fat mass fell significantly more on forskolin, lean mass trended up without reaching significance (p = 0.097), and bone mass changed. The published summary reports these body composition results rather than a difference in weight on the scale 1. Thirty men, 15 per group, is a very small trial for a headline this famous.
A companion trial gave 23 mildly overweight women the same Forslean extract. Forskolin did not produce significant changes in fat mass, lean mass or body fat percentage; the authors concluded it 'does not appear to promote weight loss but may help mitigate weight gain' 2. Women on forskolin did report less fatigue, hunger and fullness. With 7 women analyzed on the extract, this is a very small study.
Two later trials point in different directions. In 30 overweight adults told to follow a calorie-reduced diet for 12 weeks, waist and hip size fell just as much on placebo as on 250 mg of Coleus extract twice a day; the extract group did see lower fasting insulin and insulin resistance 3. A 2026 trial of a different extract, Forcslim, in 60 overweight adults found about 1.93 kg more weight loss and 1.83 cm more off the waist than placebo, plus lower triglycerides and higher HDL cholesterol 4. That trial was quasi-randomized (participants were not fully randomly assigned), which weakens it.
Put together, that is Limited evidence for a small body composition effect, mostly in men, from trials with 30 or fewer people per study. If body composition is the goal, the lean body mass calculator and TDEE calculator give you numbers that diet and training change far more reliably than any extract.
Does forskolin raise testosterone?
In the 30-man trial, free testosterone (the share not bound to proteins) rose significantly on forskolin compared with placebo. Total testosterone rose by about 17% on average on forskolin and fell about 1% on placebo, but that difference was not statistically significant 1. No other trial has confirmed it, so this grades Early. Low testosterone is diagnosed with repeat morning blood tests and treated by a clinician, and forskolin is not a treatment for it. The free testosterone calculator explains how free testosterone is estimated from total testosterone, SHBG and albumin.
Blood sugar, cholesterol and other uses
In the diet trial, fasting insulin and insulin resistance improved on the extract compared with placebo, and HDL cholesterol rose in both groups 3. The Forcslim trial reported lower triglycerides and higher HDL 4. These are single small trials, so they grade Early. In a 6-month single-blinded trial of 40 people with mild or moderate asthma, 10 mg of oral forskolin a day was compared with sodium cromoglycate inhalations, and fewer people on forskolin had attacks 9; that comparison drug is rarely the standard today. Forskolin is not a treatment for asthma, which is diagnosed and treated by a clinician, and it is never a swap for a prescribed inhaler. Forskolin eye drops have been studied for glaucoma with conflicting results, and an oral supplement should never be put in the eye 5.
How much forskolin do studies use?
These are the amounts trials used, listed as research history rather than a dose for you. There is no Recommended Dietary Allowance or official upper limit for forskolin.
| Use studied | Amount per day | Form | Length | Source |
|---|---|---|---|---|
| Body composition, men | 500 mg extract (250 mg twice a day), about 50 mg forskolin | 10% Coleus forskohlii extract | 12 weeks | 1 |
| Body composition, women | 500 mg extract (250 mg twice a day) | Forslean, 10% extract | 12 weeks | 2 |
| Weight with a calorie-cut diet | 500 mg extract (250 mg twice a day) | Coleus forskohlii extract | 12 weeks | 3 |
| Asthma | 10 mg forskolin | Oral capsules | 6 months | 9 |
| Side effects in Japanese users | Diarrhea rose with dose; the authors estimated under 250 mg extract a day to avoid it, and 500 mg 'might be acceptable' | Marketed products | Survey | 6 |
One LifeFrom capsule holds 500 mg of Forslean (10% forskolin), about 50 mg of forskolin. That is the same daily total as the men's and women's trials, but those trials split it into two 250 mg doses, and a single 500 mg dose is above the amount the Japanese survey linked to fewer stomach complaints 6.
When to take coleus forskohlii
How forskolin was taken in trials
How long does forskolin take to work? The trials measured body composition at 12 weeks 123, and the changes reported were measured with body composition scans, so a bathroom scale is a poor way to judge it. Can you take it every day? The trials did, for 12 weeks. No study has followed people for longer, so long-term safety is unknown 5.
Forskolin side effects
In a nationwide online survey of Japanese users, 10.5% reported an adverse event; 92% of those were stomach and bowel symptoms and 81% were diarrhea, which became more likely as the amount of extract rose 6. In the two Forslean trials, researchers saw no clinically significant changes in blood tests, heart rate or blood pressure over 12 weeks 2, and the Forcslim trial reported the same 4. Monographs list low blood pressure, a slow or fast heart rate, headache and diarrhea as reported reactions 5.
| Common and usually mild | Needs prompt care |
|---|---|
| Loose stools or diarrhea, more likely at higher amounts 6 | Fainting, or dizziness that does not settle when you sit or lie down: same-day care |
| More frequent bowel movements | A racing, pounding or irregular heartbeat, or chest pain: same-day or emergency care |
| Headache 5 | Bleeding that will not stop, black stools or blood in urine, especially on a blood thinner: stop the supplement and get same-day care |
| Mild lightheadedness on standing | Diarrhea with signs of dehydration (very dark urine, confusion, passing little urine): same-day care |
Who should avoid forskolin or ask first
- Pregnancy and breastfeeding: no human safety data exist; the product label says to consult a healthcare professional, and it is best avoided.
- Children: trials enrolled adults; keep it out of reach of children.
- Polycystic kidney disease: forskolin may contribute to cyst enlargement, and Memorial Sloan Kettering's monograph says these patients should not use it 5. In cell and mouse models of polycystic kidney disease, cAMP switches on Runx1, a protein that drives cyst growth 10.
- Low blood pressure, heart rhythm problems or heart disease: forskolin relaxes blood vessels and affects the heart in lab studies 58. Ask your cardiologist or clinician.
- Bleeding disorders and surgery: forskolin slows platelet clumping in lab and animal studies 8. Tell your surgical team, who will usually ask you to stop supplements beforehand.
- Stomach ulcers: cAMP signaling is involved in stomach acid release; ask your clinician first.
- Taking regular medicines: see the interactions below.
Forskolin interactions
| Medicine | What can happen | Why | What to do |
|---|---|---|---|
| Blood pressure medicines (beta-blockers, ACE inhibitors, calcium channel blockers, vasodilators) | Blood pressure could drop further, causing dizziness or fainting | Forskolin relaxes blood vessels in lab studies 58 | Ask your prescriber before combining; note dizziness on standing |
| Warfarin, other anticoagulants, aspirin and antiplatelet drugs | Possible added bleeding risk | Forskolin reduced platelet aggregation in lab and animal work 8 | Ask the clinician who manages your blood thinner; tell your team before surgery |
| Nitrates and other drugs that dilate blood vessels | Added blood pressure lowering | Same vessel-relaxing effect 5 | Ask your prescriber |
| Drugs cleared by CYP3A4 (many statins, some immunosuppressants, some heart drugs) | Possibly lower drug levels | Forskolin switched on CYP3A genes in liver cells 7 and Coleus extract induced CYP enzymes in mice 11; not shown in people | Ask your pharmacist to check your list |
| Diabetes medicines | Uncertain; insulin fell in one diet trial | Effect on blood sugar not settled 3 | Tell your prescriber before combining |
Supplements to pair or keep apart
| Supplement | Together or apart | Why |
|---|---|---|
| Nattokinase and high-dose omega-3 | Ask first if on a blood thinner | Stacking supplements that affect clotting adds up; forskolin slows platelets in lab work 8 |
| Green tea extract and green coffee extract | Avoid stacking 'fat burner' products | Multiple weight-loss botanicals multiply side effects without trials of the combination |
| Creatine | Together is fine | Better evidence for lean mass and strength with training; no known interaction |
| Carnitine | Together is fine | Often chosen for training and body composition; no known interaction |
Blood tests worth knowing about
No blood test tracks forskolin itself. The tests below are the ones trials saw move, or the checks that matter for its cautions. Ask your clinician whether any of them are useful for you; a home blood pressure cuff is often the most practical check if you take blood pressure medicines.
| Marker | Why it matters with forskolin | When it is usually checked |
|---|---|---|
| Free testosterone and total testosterone | Free testosterone rose in one trial of men 1 | Morning blood test when low testosterone is suspected |
| Fasting insulin and HOMA-IR | Improved in one diet trial 3 | Insulin resistance assessment |
| HDL cholesterol and triglycerides | HDL rose and triglycerides fell in the Forcslim trial 4 | Routine lipid panel |
| Heart rate | Fast and slow heart rates are listed as reactions 5 | Any visit; a home monitor or watch also tracks it |
| Platelet count | Part of the bleeding picture if you bruise easily; forskolin affects platelet function, not number 8 | Complete blood count |
| Creatinine and eGFR | Kidney function, relevant to the polycystic kidney caution 5 | Routine metabolic panel |
Our guides to clotting tests and blood sugar explain these numbers, and the HOMA-IR calculator turns fasting glucose and insulin into an insulin-resistance score. A result outside its range is a conversation for your clinician, not a cue to start a supplement.
Forskolin in the LifeFrom pouch
| In the LifeFrom pouch | |
|---|---|
| Product | Forslean |
| What one serving holds | Forslean® (Coleus forskohlii Extract 10%), 500 mg, about 50 mg of forskolin (Daily Value not established) |
| Form | 1 capsule; vegan capsule |
| How it is packed | One serving in each of your 30 daily pouches, with up to 8 supplements per pouch |
| Price | $13.80 a month, plus the fixed $28.50 a month packing, handling and US delivery line for the whole pouch, not per supplement. Prices as of November 2026; the shop shows the current price. |
| Curated packs that include it | None |
One capsule matches the daily total of the Forslean trials, 500 mg 12, but delivers it as one dose in the morning pouch where the trials split it into two 250 mg doses, and diarrhea rose with the amount taken in the Japanese user survey 6. Forslean is not in any curated pack. You can see the shop and its packs.
This guide is general education, not medical advice. Supplements are not FDA-approved for safety or effectiveness, and forskolin's safety beyond 12 weeks is unknown. The clinician who knows your history and medicines is the right person to decide whether it fits you; see our medical disclaimer.
Citations
- Godard MP, Johnson BA, Richmond SR. Body composition and hormonal adaptations associated with forskolin consumption in overweight and obese men. Obes Res. 2005;13(8):1335-1343.
- Henderson S, Magu B, Rasmussen C, et al. Effects of coleus forskohlii supplementation on body composition and hematological profiles in mildly overweight women. J Int Soc Sports Nutr. 2005;2(2):54-62.
- Loftus HL, Astell KJ, Mathai ML, Su XQ. Coleus forskohlii extract supplementation in conjunction with a hypocaloric diet reduces the risk factors of metabolic syndrome in overweight and obese subjects: a randomized controlled trial. Nutrients. 2015;7(11):9508-9522.
- Channangihalli Thimmegowda S, Hussain Mirza FH, Venkataraman R, Nagarajaiah RB. A 12-week, double-blind, quasi-randomized, placebo-controlled study to evaluate the efficacy and safety of Coleus forskohlii (Forcslim) on body weight loss. J Int Soc Sports Nutr. 2026.
- Memorial Sloan Kettering Cancer Center. Forskolin: purported benefits, side effects and more (About Herbs). Updated September 2023.
- Nishijima C, Chiba T, Sato Y, Umegaki K. Nationwide online survey enables the reevaluation of the safety of Coleus forskohlii extract intake based on the adverse event frequencies. Nutrients. 2019;11(4):866.
- Ding X, Staudinger JL. Induction of drug metabolism by forskolin: the role of the pregnane X receptor and the protein kinase A signal transduction pathway. J Pharmacol Exp Ther. 2005;312(2):849-856.
- Christenson JT, Thulesius O, Nazzal MM. The effect of forskolin on blood flow, platelet metabolism, aggregation and ATP release. Vasa. 1995;24(1):56-61.
- González-Sánchez R, Trujillo X, Trujillo-Hernández B, et al. Forskolin versus sodium cromoglycate for prevention of asthma attacks: a single-blinded clinical trial. J Int Med Res. 2006;34(2):200-207.
- Zhang Y, Liu C, Liu J, et al. Targeting Runx1 slows cyst growth in autosomal dominant polycystic kidney disease. FASEB J. 2026.
- Yokotani K, Yamazaki Y, Shimura F, Umegaki K. Comparison of CYP induction by Coleus forskohlii extract and recovery in the small intestine and liver of mice. Biol Pharm Bull. 2020;43(1):145-152.
Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.
