Drug Interaction Report

Iron and Levodopa Oral Inhalation: Interaction Details

Name: Iron and Levodopa Oral Inhalation Interaction
Creator: Dr. Brian Staiger, PharmD, BCPS

A pharmacist-reviewed analysis of the Iron and Levodopa Oral Inhalation interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

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

Levodopa Oral Inhalation

Inbrija Inbrija®

Iron

No brand names on record

Medically reviewed by

Dr. Brian Staiger, PharmD, BCPS

Updated Aug 8, 2026

Editorial policy · Data sources

Interaction severity

Major

Potentially serious — often needs a change or close monitoring.

Minor

Moderate

Major

Contraindicated

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.

Of 37 documented Iron interactions, 4 are rated major — including this one.

Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.

Onset

unspecified

Evidence

probable

Severity

Major

What happens

Potentially reduced carbidopa or levodopa exposure and reduced efficacy of carbidopa/levodopa

Interaction Deep Dive

Concomitant use of carbidopa/levodopa with iron salts may reduce exposure and clinical effectiveness of carbidopa/ levodopa³⁵. Iron salts can form chelates with levodopa/carbidopa. If coadministered, monitor patients for worsening Parkinson’s symptoms ². Reduced systemic exposure of carbidopa and levodopa has occurred in 2 pharmacokinetic studies of coadministration with ferrous sulfate ⁷⁸. Therefore, use caution with coadministration of carbidopa/levodopa with iron salts ¹. Separate administration with ferric maltol by at least 2 hours ⁶.

Why it happens (mechanism)

Formation of chelates that reduce carbidopa and levodopa bioavailability

Literature reports

2 reports — tap to read

a) In a pharmacokinetic study of patients with Parkinson disease (n=9), coadministration of ferrous sulfate 325 mg with carbidopa 25 mg/levodopa 100 mg resulted in a 30% decrease of levodopa AUC and more than 75% reduction of carbidopa AUC. Carbidopa/levodopa clinical efficacy was not significantly effected in this single-dose coadministration study ⁷.

b) In a pharmacokinetic study of healthy subjects (n=8), coadministration of a single dose of ferrous sulfate 325 mg with levodopa 250 mg resulted in a 55% reduction of Cmax and a 51% reduction of levodopa AUC ⁸.

Common questions

Can I take Iron and Levodopa Oral Inhalation together?

Potentially reduced carbidopa or levodopa exposure and reduced efficacy of carbidopa/levodopa Always confirm with your pharmacist or prescriber before making any change.

How serious is the Iron and Levodopa Oral Inhalation interaction?

It is rated major. Potentially serious — often needs a change or close 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 "probable". Good supporting evidence, though not definitively proven.

From our Q&A

Real reader questions about these medications, each personally answered by our pharmacist:

Questions for your pharmacist

Does my dose of Iron or Levodopa Oral Inhalation 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 a safer alternative to one of these medications for me?

References (8)

Product Information: LODOSYN(R) oral tablets, carbidopa oral tablets. Valeant Pharmaceuticals North America LLC (per FDA), Bridgewater, NJ, 2014. DailyMed
Product Information: CREXONT(TM)oral extended-release capsules, carbidopa, levodopa oral extended-release capsules. Amneal Specialty (per FDA), Bridgewater, NJ, 2024. DailyMed
Product Information: SINEMET(R) oral tablets, carbidopa levodopa oral tablets. Merck Sharp & Dohme Corp. (per DailyMed), Whitehouse Station, NJ, 2013. DailyMed
Product Information: SINEMET(R) CR oral sustained release tablets, carbidopa levodopa oral sustained release tablets. Merck Sharp & Dohme Corp. (per DailyMed), Whitehouse Station, NJ, 2013.
Product Information: PARCOPA(R) oral disintegrating tablets, carbidopa levodopa oral disintegrating tablets. Azur Pharma, Inc. (per manufacturer), Philadelphia, PA, 2011. DailyMed
Product Information: Feraccru oral capsules, ferric maltol oral capsules. Iron Therapeutics (UK) Ltd (per EMA), Gateshead Quays, United Kingdom, 2016. DailyMed
Campbell NR, Rankine D, Goodridge AE, et al: Sinemet-ferrous sulphate interaction in patients with Parkinson's disease. Br J Clin Pharmacol 1990; 30:599-605. PubMed
Campbell NR & Hasinoff B: Ferrous sulfate reduces levodopa bioavailability: chelation as a possible mechanism. Clin Pharmacol Ther 1989; 45:220-225. DOI

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HelloPharmacist doesn't license one of the big commercial interaction databases, so what you'll find here is not a complete list of every known drug interaction. Instead, each entry is researched, analyzed, and written up individually — documented from the published literature, reviewed by a pharmacist, and cited so you can check every source yourself.

If a combination isn't listed here, it means we haven't documented it yet — never that it's safe. For screening a full medication list, we recommend pairing this site with a comprehensive tool like the Drugs.com Interaction Checker and, most importantly, a review by your own pharmacist. For a deep, plain-English, fully sourced explanation of a specific documented interaction — that's exactly what we built this for.

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