drug-interaction-checker

drug-interaction-checker is a skill for Claude Code, Codex from langcare/langcare-mcp-fhir. It costs 89 tokens per session (2,631 once invoked), scanned A, original, MIT.

A medication interaction checker that compares active prescriptions in pairs and classifies possible drug-to-drug conflicts by seriousness, including conflicts involving CYP450 drug-processing pathways.

In plain words
What is it for?
Use it to review active medicines, identify contraindicated or major interactions, examine CYP450 conflicts, and consider alternatives for serious findings.
Why use it?
It helps uncover combinations that may be unsafe, especially when age, other illnesses, allergies, or kidney and liver function change the risk.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to review active medicines, identify contraindicated or major interactions, examine CYP450 conflicts, and consider alternatives for serious findings.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/langcare/langcare-mcp-fhir/drug-interaction-checker
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add langcare/langcare-mcp-fhir --skill drug-interaction-checker
Clone the repo
git clone --depth 1 https://github.com/langcare/langcare-mcp-fhir

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for drug-interaction-checker

README.md
[![agentmods](https://agentmods.dev/badge/skills/langcare/langcare-mcp-fhir/drug-interaction-checker/github.svg)](https://agentmods.dev/skills/langcare/langcare-mcp-fhir/drug-interaction-checker)
Your own site
<a href="https://agentmods.dev/skills/langcare/langcare-mcp-fhir/drug-interaction-checker"><img src="https://agentmods.dev/badge/skills/langcare/langcare-mcp-fhir/drug-interaction-checker/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for drug-interaction-checker

Your own site · 80×15
<a href="https://agentmods.dev/skills/langcare/langcare-mcp-fhir/drug-interaction-checker"><img src="https://agentmods.dev/badge/skills/langcare/langcare-mcp-fhir/drug-interaction-checker.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 89 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,631 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00089 $0.02631
Opus 5 $0.00044 $0.01316
Sonnet 5 $0.00018 $0.00526
Haiku 4.5 $0.00009 $0.00263

Measured 9d ago against content hash 7d5f4028c36e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

drug-interaction-checker scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/core/medication-management/drug-interaction-checker/SKILL.md · 264 lines

How it starts

The opening of the file, as written. The whole thing — 264 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Drug Interaction Checker

Overview

Pull all active medications for a patient, cross-reference each pair against known major drug-drug interaction databases, classify by severity (contraindicated, major, moderate, minor), identify CYP450 pathway conflicts, and suggest therapeutic alternatives when significant interactions are detected.

FHIR Resources Used

Resource Purpose Key Fields
MedicationRequest Active prescribed medications status, medicationCodeableConcept, dosageInstruction
MedicationStatement Patient-reported medications including OTC status, medicationCodeableConcept, dosage
Patient Patient demographics, age for risk stratification birthDate, gender
Condition Comorbidities affecting interaction severity code, clinicalStatus
Observation Renal/hepatic function affecting drug metabolism code, valueQuantity
AllergyIntolerance Cross-sensitivity patterns code, reaction

Instructions

Step 1: Verify Patient and Retrieve Demographics

Tool: fhir_read
resourceType: "Patient"
id: "[patient-id]"

Extract age, gender, weight if available. Age and organ function affect CYP450 metabolism rates.

Step 2: Pull All Active Medications

2a: Prescribed medications

Tool: fhir_search
resourceType: "MedicationRequest"
queryParams: "patient=[patient-id]&status=active&_count=100"

2b: Patient-reported medications (includes OTC, supplements)

Tool: fhir_search
resourceType: "MedicationStatement"
queryParams: "patient=[patient-id]&status=active&_count=100"

Merge both lists. Deduplicate by RxNorm code (system: http://www.nlm.nih.gov/research/umls/rxnorm).

Step 3: Pull Renal and Hepatic Function

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=33914-3,48642-3,69405-9,77147-7&_sort=-date&_count=4"

LOINC codes:

  • 33914-3: eGFR (CKD-EPI)
  • 48642-3: eGFR for African American
  • 69405-9: Glomerular filtration rate
  • 77147-7: eGFR (CKD-EPI 2021)

Read the full file on GitHub · 264 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 264 lines · 89 tokens per session scan A 7d5f4028c36e

Subscribe to this mod's changes

drug-interaction-checker is a skill published in the GitHub repository langcare/langcare-mcp-fhir (55 stars, last pushed 5mo ago), licensed MIT. It adds 89 tokens to every session and 2,631 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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