Levothyroxine
Severe
Database
Resin binds thyroxine in gut
Separate by ≥4 h; monitor TSH
Source: Kimi deep-research + Cla
Drug reference
Cholestyramine
Bile acid sequestrant (anion-exchange resin) · Antilipidemic
Also known as Cholestyramine resin, Questran, Prevalite, LoCHOLEST, Cholesguard, Cholesta
START
4 g PO once–twice daily, mixed in fluid
TYPICAL MAX
24 g/day
STOP IF
Severe constipation/obstruction or bleeding (vit K)
WATCH
Bowel habit, fat-soluble vitamins, INR if on warfarin
CDSCO approvedSchedule HATC C10AC01
KDIGO 2024 + manufacturer label
- ONSET
- 1w · LDL effect
- PEAK
- 3w · max effect ~3 wk
- t½
- 36s · not absorbed
- DURATION
- 1d · dosing-bound
EXCRETION
Faecal — resin–bile-acid complex
route + CYP
INTERACTIONS
9 major
SEVERE in our sources
PREGNANCY
Not systemically absorbed — acceptable; monitor fat-soluble vitamins.
FDA category + note
Top interactionssee all 12 →
- LevothyroxineSevereDatabaseKimi deep-research + Cla
- MycophenolateSevereDatabase
- Mycophenolate MofetilSevereDatabaseDDInter
- Mycophenolate SodiumSevereDatabase
Available in India
3 branded formulations. Look up specific brands in the Drugs workspace.
Mechanism
Non-absorbed resin that binds bile acids in the gut, interrupting enterohepatic recirculation; upregulates hepatic LDL receptors (lowering LDL-C) and increases faecal bile-acid excretion.
Indications
Primary hypercholesterolaemiaPruritus from partial biliary obstruction/cholestasisBile acid diarrhoeaAdjunct in some toxin/drug elimination (e.g., leflunomide washout)
Dosing
- Adult
- 4 g PO once–twice daily initially; usual 12–24 g/day in 1–4 divided doses (mixed in fluid).
- Pediatric
- 240 mg/kg/day in 2–3 divided doses (max ~8 g/day).
- Renal adjustment
- No adjustment (not absorbed).
- Hepatic adjustment
- No adjustment; ineffective in complete biliary obstruction.
- Geriatric
- Constipation risk; start low.
- Max dose
- 24 g/day
Pharmacokinetics
Onset
LDL reduction within ~1–2 weeks; pruritus relief days
Peak effect
Maximal lipid effect ~2–4 weeks
Duration
Duration of dosing (not absorbed)
Half-life
Not applicable (non-absorbed resin)
Bioavailability
Negligible (acts in gut lumen)
Protein binding
Not applicable
Metabolism
Not metabolised
Excretion
Faecal (resin–bile-acid complex)
Contraindications
- Complete biliary obstruction
- Hypersensitivity
- Caution in constipation/phenylketonuria (aspartame forms)
Side effects
Common
ConstipationBloating/flatulenceNauseaAbdominal discomfort
Serious
- Fat-soluble vitamin (A,D,E,K) deficiency
- Hyperchloraemic acidosis (children, high dose)
- GI obstruction (rare)
- Bleeding (vitamin K depletion)
Pregnancy & lactation
Pregnancy
Not systemically absorbed — acceptable; monitor fat-soluble vitamins.
Lactation
Not absorbed; compatible (monitor maternal vitamin status).
Drug interactions
Mycophenolate
Severe
Database
40% reduction in MPA levels, rejection risk
Avoid combination.
Mycophenolate Mofetil
Severe
Database
Drug interaction classified as: absorption
Source: DDInter
Mycophenolate Sodium
Severe
Database
Significantly reduced MPA exposure (AUC), potentially leading to a substantial decrease in immunosuppressive efficacy and increased risk of rejection.
Avoid concomitant use if possible. If co-administration is unavoidable, separate administration by several hours (e.g., mycophenolate 2 hours before or 4-6 hours after cholestyramine) and closely monitor mycophenolate levels and clinical response. Significant dose increase of mycophenolate may be necessary.
Mycophenolic Acid
Severe
Database
Drug interaction classified as: absorption
Source: DDInter
Raloxifene
Severe
Database
Markedly reduced raloxifene absorption (interrupts enterohepatic recycling)
Do not co-administer; separate timing
Source: Kimi deep-research + Cla
Teriflunomide
Severe
Database
Drug interaction classified as: absorption, metabolism
Source: DDInter
Thyroxine
Severe
Database
Significantly decreased thyroxine efficacy, leading to severe hypothyroidism symptoms or increased TSH levels
Administer thyroxine at least 4-5 hours before or after cholestyramine. Monitor TSH levels closely and adjust thyroxine dose as needed.
Warfarin
Severe
Database
Reduced warfarin + vitamin K absorption
Separate dosing; monitor INR
Source: Kimi deep-research + Cla
Alirocumab
Moderate
Textbook
Reduced efficacy of statins.
Patients should take other medications 1 h before or 3 to 4 h after a dose of cholestyramine.
Source: G&G 14e · p738
Atorvastatin + Aspirin
Moderate
Textbook
Reduced efficacy of statins.
Patients should take other medications 1 h before or 3 to 4 h after a dose of cholestyramine.
Source: G&G 14e · p738
Evolocumab
Moderate
Textbook
Reduced efficacy of statins.
Patients should take other medications 1 h before or 3 to 4 h after a dose of cholestyramine.
Source: G&G 14e · p738
Related guidelines
Ask House about Cholestyramine
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e, Goodman & Gilman 14e, Katzung, BNF·Verified: 2026-05-20 · House clinical team·Cockpit curated: 2026-05-20