Cascara sagradaBotanical

• Short-term constipationPossibly helps

  This is essentially the only thing cascara sagrada is used for [2].
  
  A pharmacist-reviewed commercial database rates it Possibly Effective for constipation, on the strength of its laxative action in some people [3].
  
  That rating rests on pharmacological plausibility and historical use, not on cited randomized trials [3]. ^[3]

• What the higher-tier review actually foundPossibly helps

  ⚠ The source tiers disagree here, and the gap between them is large.
  
  A BMJ Clinical Evidence systematic review states it found no clinically important results from RCTs on cascara in adults with idiopathic chronic constipation [7].
  
  Its wording is blunter still: it found no systematic review and no RCTs at all [7].
  
  So a commercial database says possibly effective, while a higher-tier source says the trial evidence essentially does not exist [3][7]. ^[7]

• Bowel preparation before colonoscopyNot shown to help

  Combined with magnesium sulfate or milk of magnesia, cascara does not improve bowel preparation before colonoscopy [3].
  
  The same database rates it Possibly Ineffective for that specific use [3]. ^[3]

• Traditional usesPossibly helps

  Historical use also covers gallstones, liver ailments, cancer and a general bitter-tonic role [2].
  
  A commercial database rates the evidence for all of those as insufficient to rate effectiveness [3]. ^[3]

• Dried, aged barkEvery commercial oral product starts from this

  Elemental content

  Bark of Rhamnus purshiana (Frangula purshiana), aged before sale

  Absorption

  The aging matters — fresh unaged bark causes far more intense vomiting, nausea and griping abdominal pain

  Best for

  Every commercial oral product starts from this [1]

• Tablets, capsules, powder, tea, syrupNothing consistent. Two brands at the same labelled dose may not act the same way

  Elemental content

  Unstandardized whole bark, typically around 300 mg per dose

  Absorption

  Cascaroside content varies with growing region, weather, harvest timing and processing

  Best for

  Nothing consistent. Two brands at the same labelled dose may not act the same way [2][3]

• Aromatic fluid extractLiquid dosing where a tablet is not wanted

  Elemental content

  Concentrated liquid extract of the bark

  Absorption

  Typical dose about 1 mL

  Best for

  Liquid dosing where a tablet is not wanted [11]

• Bitterless extract (food flavoring)Flavoring, and nothing else. FDA's GRAS status covers only this use, never the laxative one

  Elemental content

  Cascara extract with the bitterness removed

  Absorption

  Used in small amounts as a flavoring in some foods and beverages

  Best for

  Flavoring, and nothing else. FDA's GRAS status covers only this use, never the laxative one [2]

• Common effects

  Stomach cramping and discomfort, diarrhea, nausea and vomiting, plus reddish-brown or bright yellow urine discoloration [1][2].
  
  Less common but serious: electrolyte imbalance, especially low potassium, and allergic reactions [2][3]. ^[1]

• The FDA pulled it from OTC laxatives in 2002

  The FDA determined that cascara sagrada, along with aloe, was not generally recognized as safe and effective for over-the-counter laxative use [4].
  
  That followed manufacturers failing to submit the requested mutagenicity, genotoxicity and carcinogenicity data [4].
  
  Removal from OTC laxative products was ordered by November 5, 2002 [4].
  
  It is still sold as a dietary supplement, a category the FDA does not review for safety or effectiveness before sale [2]. ^[4]

• Liver injury

  NIH's LiverTox documents rare but sometimes severe liver injury with long-term or high-dose use, including cases with acute liver failure, ascites and portal hypertension [1].
  
  Those cases usually resolved after stopping [1].
  
  ⚠ LiverTox contradicts itself on mechanism, and we are showing both halves.
  
  It attributes injury to direct toxicity of anthraquinone derivatives [1]. Then it notes the clinical pattern — onset from days to 2 months, mixed hepatocellular and cholestatic patterns, inconsistent autoimmune markers — points to an idiosyncratic cause instead [1].
  
  It also raises the possibility that injury blamed on cascara came from an undisclosed contaminant [1]. ^[1]

• Laxative dependency and cathartic colon

  Use beyond about two weeks is linked to the colon losing its ability to produce a bowel movement without a laxative, known as cathartic colon [1][8].
  
  A government source on laxatives links chronic stimulant laxative use to loss of colonic haustral folds, suggestive of neuronal or muscular injury [6].
  
  Melanosis coli, a darkening of the colon lining, also shows up with long-term use [1][2]. ^[1]

• Conditions that rule it out

  Gut blockage or tear, ulcerative colitis, Crohn's disease, appendicitis, fecal impaction, GI bleeding and unexplained abdominal pain are all contraindications [2][3].
  
  So are kidney or liver problems, and known allergy to cascara or Rhamnus purshiana [3]. ^[3]

• Children

  Children are considered more likely than adults to become dehydrated, or harmed by potassium loss, from cascara [3].
  
  Multiple sources say plainly that it is possibly unsafe for children, or should not be given to them at all [5][8]. ^[3]

• Pregnancy and breastfeeding

  Not enough is known for any source to call cascara safe in pregnancy, so the consistent advice is to avoid it [2][3].
  
  It is considered possibly unsafe while breastfeeding too, since it passes into breast milk and can cause diarrhea in a nursing infant [5]. ^[2]

• Digoxin

  Cascara's laxative effect depletes potassium, and low potassium raises digoxin's side-effect risk [2].
  
  Drug references rate this interaction as moderate [3]. ^[2]

• Corticosteroids and diuretics

  Corticosteroids — dexamethasone, hydrocortisone, methylprednisolone, prednisone — lower potassium on their own [3].
  
  So do diuretics such as chlorothiazide, chlorthalidone, furosemide and hydrochlorothiazide [3]. Stacking either with cascara raises the risk of excessive potassium loss [2]. ^[3]

• Warfarin

  Cascara-induced diarrhea can amplify warfarin's blood-thinning effect [2].
  
  That means a higher bleeding risk for as long as the two overlap [3]. ^[2]

• Other stimulant laxatives and licorice

  Bisacodyl, senna, and large amounts of licorice each compound dehydration and electrolyte loss when stacked with cascara [2][3]. ^[2]

• Any oral medicine taken nearby

  Cascara speeds transit through the gut, which can reduce absorption of other oral medicines taken around the same time [2].
  
  Sources describe cascara's interactions overall as not fully understood, with incomplete research behind them [2]. ^[2]

Cascara sagrada is not a dietary nutrient, and has no food sources in the usual sense [2].

It comes from one tree's bark and is taken deliberately, not picked up incidentally through eating [1].

The single food-related use: a bitterless cascara extract holds FDA GRAS status as a flavoring agent, in small amounts, in some foods and beverages [2]. That is a flavoring role at flavoring quantities, nowhere near a laxative dose.

No source gives cascara-specific timing, which follows from it having had no official product labelling since 2002 [4].

What exists is class-level. WebMD says cascara, like other stimulant laxatives, can bring on a bowel movement within 12 hours [2].

The UK's NHS instructs taking senna — same drug class — at bedtime, because it takes about 8 hours to work, producing a movement the next morning [10].

Bedtime is the common practical approach for the class on that basis. Read it as an inference from the drug class, not as a cascara-specific instruction.