Drug Interaction Report

Cysteamine and Lanthanum: Interaction Details

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Lanthanum

Fosrenol®
+

Cysteamine

No brand names on record
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Updated Aug 8, 2026
LinkedIn
Interaction severity
Moderate
Can be significant — usually manageable with monitoring.
How we grade severity & evidence

Severity levels

  • Contraindicated: These should generally not be used together.
  • Major: Potentially serious — often needs a change or close monitoring.
  • Moderate: Can be significant — usually manageable with monitoring.
  • Minor: Usually limited clinical impact.

Evidence grades

  • Established: Well documented — supported by controlled studies or strong clinical data.
  • Probable: Good supporting evidence, though not definitively proven.
  • Suspected: Some evidence suggests this interaction, but it is not well established.
  • Possible: Limited or conflicting evidence; the interaction may occur.
  • Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.

Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.

Onset
unspecified
Evidence
theoretical
Severity
Moderate

What happens

Altered cysteamine pharmacokinetics and increased WBC cystine concentration

Interaction Deep Dive

Concomitant administration of cysteamine and this drug may result in altered cysteamine pharmacokinetics and increased WBC cystine concentration. Give cysteamine 1 hour before or 1 hour after this drug1.

Why it happens (mechanism)

Unknown

Common questions

Can I take Cysteamine and Lanthanum together?

Altered cysteamine pharmacokinetics and increased WBC cystine concentration Always confirm with your pharmacist or prescriber before making any change.

How serious is the Cysteamine and Lanthanum interaction?

It is rated moderate. Can be significant — usually manageable with monitoring.

How quickly could this interaction happen?

The documented onset is "unspecified". The timing of this interaction is not well characterized.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Cysteamine or Lanthanum need adjusting while I take them together?
  • What symptoms should prompt me to call you or my prescriber right away?
  • Does the timing of my doses matter for this combination?
  • Is there anything you'd monitor while I'm on both?

References (1)

  1. Product Information: PROCYSBI(R) oral delayed release capsules, cysteamine bitartrate oral delayed release capsules. Horizon Pharma USA, Inc. (per manufacturer), Lake Forest, IL, 2017. DailyMed
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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.