What is drug-interaction-checker?

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.

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

It helps uncover combinations that may be unsafe, especially when age, other illnesses, allergies, or kidney and liver function change the risk.

drug-interaction-checker — Skill for Claude Code and Codex by langcare

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.

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.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00089	$0.02631
Opus 5.5	$0.00036	$0.01052
Sonnet 5.5	$0.00018	$0.00526
Haiku 4.5	$0.00009	$0.00263

Measured 2mo ago against content hash 7d5f4028c36e, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 2mo 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.

2mo 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 (71 stars, last pushed 6mo ago), licensed MIT. It adds 89 tokens to every session and 2,631 once invoked, about $0.0004 per session on Opus 5.5. 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.

Scientific

drug-interaction-checker next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
drug-interaction-checkerlangcare/langcare-mcp-fhir	Skill	71	6mo ago	MIT	A	89	Claude Code, Codex
instrument-data-to-allotropeanthropics/knowledge-work-plugins	Skill	35k	2d ago	Apache-2.0	A	123	Claude Code
exploratory-data-analysisK-Dense-AI/scientific-agent-skills	Skill	56k	4d ago	MIT	A	83	Claude Code
matlabK-Dense-AI/scientific-agent-skills	Skill	56k	4d ago	MIT	A	44	Claude Code
phylogeneticsK-Dense-AI/scientific-agent-skills	Skill	56k	4d ago	MIT	A	71	Claude Code, Codex
research-engineerdavila7/claude-code-templates	Skill	33k	yesterday	MIT	A	43	Claude Code, Codex
mapping-to-snomedmaziyarpanahi/openmed	Skill	5.8k	yesterday	Apache-2.0	A	205	Claude Code