Written by Katja Boehm and the CAM-Cancer Consortium.
Updated April 29, 2016


Is it safe?

The safety of Carctol has so far not been systematically assessed. The distributors of the remedy claim that Carctol is not associated with adverse effects or herb-drug interacdtions, but information on adverse effects and interactions is available for the individual plants Carctol contains. These do not necessarily refer to the dosages used in Carctol.

Adverse effects

No adverse effects of Carctol have been reported. One of the ingredients of Carctol, Himalayan rhubarb (Rheum acuminatum), has been linked with adverse effects such as bone loss and muscle weakness. Rhubarb can also cause anaphylaxis, diarrhoea, heart arrhythmias, depletion of potassium and other electrolytres.9 There is one report of a four-year old who ingested rhubarb leaves containing oxalic acid and died.10 Orally, rhubarb can cause cramp-like or spasmodic GI discomfort, watery diarrhoea and uterine contractions. When consuming sarsaparilla in excessive amounts, gastrointestinal (GI) irritation or temporary kidney impairment may occur due to it saponin constituents. Orally, ingesting large amounts of garden cress may cause GI irritations. Java pepper (Piper cubeba L.) and Puncture vine (Tribulus terrestris) can have psychoactive effects.


None known.


Sarsaparilla can interact with digitalis by increasing the glycoside absorption. Theoretically, sarsaparilla may alter the absorption or elimination of simultaneously administered herbs. Sarsaparilla may interact with digoxin (Lanoxin) as it may increase digitalis glycoside absorption.5

Theoretically, due to reports that cubebs increases stomach acid, cubebs might decrease the effectiveness of antacids and H2-blockers cimetidine (Tagamet), ranitidine (Zantac), nizatidine (Axid) and famotidine (Pepcid). Cubebs might also decrease the effectiveness of proton pump inhibitors including omeprazole (Prilosec), lansoprazole (Prevacid), rabeprazole (Aciphex), pantoprazole (Protonix) and esomeprazole (Nexium).

Theoretically, puncture vine might enhance the blood glucose-lowering effect of hypoglycaemic drugs, including glimepiride (Amaryl), glyburide (Diabeta, Glynase PresTabs, Micronase), insulin, metformin (Glucophage), pioglitazone (Actos), and rosiglitazone (Avanida).

Concurrent use of rhubarb might decrease mineral absorption. Overuse of rhubarb might cause potassium depletion, increasing the risk of cardio toxicity and digoxin toxicity. Overuse might compound corticosteroid-induced or diuretic-induced potassium loss (diuretics include chlorothiazide (Diuril), chlorthalidone (Thalitone), furosemide (Lasix), and hydrochlorothiazide (HCTZ, Hydrodiuril, Microzide).

No interactions of garden cress with herbs, supplements or other drugs are known..


Patients are advised to drink three to five litres of water each day and to follow a vegetarian diet. This could possibly lead to malnutrition and fluid congestion. There is no data on the use of Carctol during pregnancy and lactation.

Quality issues

There are no independent assessments of the quality of Carctol.

Citation Katja Boehm, CAM-Cancer Consortium. Carctol [online document]. http://ws.cam-cancer.org/The-Summaries/Herbal-products/Carctol. April 29, 2016.


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