Can you take Bile acid sequestrants with Vitamin D3 (Cholecalciferol)?
This is general information, not medical advice. Supplements can interact with medicines and health conditions. Always check with your doctor or pharmacist before starting or changing supplements.
What the evidence says
Bile acid sequestrants like cholestyramine work by binding bile acids in the gut, and your body needs those same bile acids to absorb fat-soluble vitamins such as vitamin D. A clinical reference on this drug class specifically names vitamin D among the fat-soluble vitamins it can deplete, recommending vitamins be taken a full 4 hours before the sequestrant dose; a separate clinical reference on cholestyramine specifically gives the more general rule of spacing other oral substances 1 hour before or 4 hours after it. Rather than track two slightly different windows, the safest and simplest instruction is to keep a full 4-hour gap between your vitamin D3 dose and your sequestrant dose, on either side. A 1978 case report of osteomalacia (bone softening from vitamin D deficiency) in a patient on cholestyramine illustrates the risk in practice, though that patient had also had ileal surgery, which independently impairs vitamin D absorption, so it doesn't isolate cholestyramine's effect on its own. If you take a sequestrant long-term, ask your doctor about periodic vitamin D level checks.
Keep at least 4 hours between them.
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We check against a limited set of medications. Absence of a warning here is not evidence of safety. Always confirm with your pharmacist.