Drug Interaction Checker

What Drug Interaction Checker does

Drug Interaction Checker MCP server exposes medication lookup and clinical reference operations through the Model Context Protocol. It is designed for agents that need to examine drug combinations, standardize names, retrieve labeled dosing information, or suggest drugs within the same therapeutic class.

The service uses RxNorm from the U.S. National Library of Medicine for drug normalization and interaction-related lookups. DailyMed supplies FDA-labeled dosing guidance, while openFDA Drug Label is listed among the upstream public-domain sources. The hosted deployment runs at https://drug-interaction-mcp.atlasword.workers.dev/mcp.

How it works

Clients send MCP JSON-RPC 2.0 requests over HTTP POST. Tool discovery is available through tools/list, and individual operations are invoked with tools/call. Requests can include an Authorization: Bearer <api_key> header. Anonymous callers can use the free tier for up to 100 calls per month per IP; paid tiers provide higher monthly and rate limits.

check_interaction compares two drugs and reports a severity category—contraindicated, major, moderate, or minor—along with the mechanism when known and its source. check_interactions_multi examines a list of two to eight drugs pairwise, removes duplicate directions such as A-B and B-A, and evaluates up to 28 pairs.

Setup and configuration

The quickest connection method is mcp-remote pointed at the hosted MCP endpoint. Supply the Bearer token as a request header, then add the resulting command to an MCP client configuration. The README provides configurations for Cursor and Claude Desktop; after restarting either client, the tools should be available in its MCP interface.

A key can be obtained through the hosted upgrade flow for Solo, Team, or Pro access. The service also supports anonymous free-tier requests. The endpoint exposes a /health route for liveness checks. No local database or application-specific environment variable is described for client setup.

Tools and capabilities

• check_interaction: inspect a two-drug combination and return severity, mechanism when available, and source.
• check_interactions_multi: review polypharmacy lists containing two to eight drugs.
• normalize_drug_name: map a brand or generic name to an RxNorm record with RxCUI, generic name, brands, and synonyms.
• dose_guide: retrieve FDA-labeled dosing guidance from DailyMed. This tool requires Team or Pro access.
• find_alternatives: find drugs in the same ATC therapeutic class. This tool also requires Team or Pro access.

The Drug Interaction Checker MCP server is suited to medication reconciliation assistants, drug-information agents, and clinical decision-support copilots that need source-backed lookups rather than an embedded medication database.

Limitations and notes

The Drug Interaction Checker MCP server is a transport, authentication, and caching layer over upstream sources, not an independent clinical knowledge base. Interaction results depend on the available RxNorm, DailyMed, and openFDA data.

Anonymous and Free-tier callers receive tier_required errors for the dosing and alternatives tools. Usage is subject to monthly call caps and per-minute rate limits: Free provides 100 calls per month, while Solo, Team, and Pro provide 2,000, 10,000, and 50,000 calls respectively. Treat returned information as reference data for an appropriate clinical workflow.