Background

Coleus is a plant from the mint family. It grows in tropical regions of Asia such as Nepal, India, and Thailand. The root is used as medicine. Coleus root contains a chemical called forskolin. Herbal product manufacturers often produce coleus extracts that contain high levels of forskolin. These preparations are being promoted for the same conditions for which forskolin has been traditionally used.

Coleus or forskolin are used for high blood pressure, chest pain (angina), asthma, dry eye, and many other conditions, but there is no good scientific evidence to support any of these uses.

Safety Safety definitions

When taken by mouth: Coleus is POSSIBLY SAFE for most adults when taken by mouth in appropriate amounts. Coleus seems to be safe in doses of 500 mg or less. But coleus is POSSIBLY UNSAFE when taken in larger doses. It can cause diarrhea, loose stools, and other side effects.

When given by IV: Coleus is POSSIBLY SAFE for most adults when given by IV. It can cause flushing and low blood pressure.

When inhaled: Coleus is POSSIBLY SAFE for most adults when inhaled (breathed in). It can cause throat irritation, cough, tremor, and restlessness.

When applied into the eye: Coleus is POSSIBLY SAFE for most adults when applied as eye drops. Eye drops containing coleus can cause stinging.

Special Precautions & Warnings:

Pregnancy: Coleus is POSSIBLY UNSAFE when used during pregnancy. High doses of coleus might slow or stop the growth of the fetus. Stay on the safe side and avoid use.

Breast-feeding: There is not enough reliable information about the safety of taking coleus if you are breast-feeding. Stay on the safe side and avoid use.

Bleeding disorders: Coleus contains a chemical called forskolin that might increase the risk of bleeding in some people.

Heart disease: Coleus contains a chemical called forskolin that might lower blood pressure. There is some concern that coleus might interfere with treatment for heart or blood vessel diseases and could make these conditions worse. Use coleus with caution if you have a heart problem.

Low blood pressure: Coleus contains a chemical called forskolin that might lower blood pressure. If your blood pressure is already low, taking coleus might make it drop too much.

Surgery: Coleus contains a chemical called forskolin that might increase bleeding during and after surgery. Stop using coleus at least 2 weeks before a scheduled surgery.

Effectiveness

Dosing & administration

The appropriate dose of coleus depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for coleus. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.

Interactions with pharmaceuticals

Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)

Interaction Rating=Moderate Be cautious with this combination.

Some medications are changed and broken down by the liver. Coleus might affect how quickly the liver breaks down some medications.
Some medications that are changed by the liver include amitriptyline (Elavil), diazepam (Valium), zileuton (Zyflo), celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), warfarin (Coumadin), and others.

Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)

Interaction Rating=Moderate Be cautious with this combination.

Some medications are changed and broken down by the liver. Coleus might increase how quickly the liver breaks down some medications. Taking coleus along with some medications that are broken down by the liver can decrease the effectiveness of some medications. Before taking coleus, talk to your healthcare provider if you are taking any medications that are changed by the liver.
Some medications changed by the liver include lovastatin (Mevacor), ketoconazole (Nizoral), itraconazole (Sporanox), fexofenadine (Allegra), triazolam (Halcion), and many others.

Medications for high blood pressure (Antihypertensive drugs)

Interaction Rating=Moderate Be cautious with this combination.

Coleus might decrease blood pressure. Taking coleus along with medications for high blood pressure might cause your blood pressure to go too low.

Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDIURIL), furosemide (Lasix), and many others.

Medications for high blood pressure (Calcium channel blockers)

Interaction Rating=Major Do not take this combination.

Coleus might decrease blood pressure. Calcium channel blockers are a type of medicine used to decrease blood pressure. Taking coleus with calcium channel blockers might cause your blood pressure to go too low. Don't use coleus if you are taking calcium channel blockers.

Some calcium channel blockers include nifedipine (Adalat, Procardia), verapamil (Calan, Isoptin, Verelan), diltiazem (Cardizem), isradipine (DynaCirc), felodipine (Plendil), amlodipine (Norvasc), and others.

Medications that increase blood flow to the heart (Nitrates)

Interaction Rating=Major Do not take this combination.

Coleus increases blood flow. Taking coleus with medications that increase blood flow to the heart might increase the chance of dizziness and lightheadedness. Don't use coleus if you are taking medications that increase blood flow to the heart.

Some of these medications that increase blood flow to the heart include nitroglycerin (Nitro-Bid, Nitro-Dur, Nitrostat) and isosorbide (Imdur, Isordil, Sorbitrate).

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Interaction Rating=Moderate Be cautious with this combination.

Coleus might slow blood clotting. Taking coleus along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.

Warfarin (Coumadin)

Interaction Rating=Moderate Be cautious with this combination.

Coleus might change how your body breaks down warfarin. Be watchful of this combination and talk to your health provider.

Interactions with herbs & supplements

Herbs and supplements that might lower blood pressure: Early research shows that coleus may lower blood pressure. Using it along with other herbs and supplements that also lower blood pressure might cause your blood pressure to become too low. Some of these herbs and supplements include andrographis, casein peptides, cat's claw, coenzyme Q-10, fish oil, L-arginine, lycium, stinging nettle, theanine, and others.
Herbs and supplements that might slow blood clotting: Coleus might slow blood clotting. Taking coleus along with herbs and supplements that also slow clotting might increase the chances of bruising and bleeding.

Some of these herbs include angelica, anise, arnica, asafetida, bogbean, boldo, capsicum, celery, chamomile, clove, danshen, fenugreek, feverfew, garlic, ginger, ginkgo, Panax ginseng, horseradish, licorice, meadowsweet, prickly ash, onion, papain, passionflower, poplar, quassia, red clover, turmeric, wild carrot, wild lettuce, willow, and others.

Interactions with foods

There are no known interactions with foods.

Action

Forskolin works on muscles in the heart and in the walls of the blood vessels. It produces a more powerful heartbeat and widening of the blood vessels, which lowers blood pressure.