OnLabel

A self-verifying OTC medication safety assistant for US consumers.

Generic AI chat will happily tell you "Tylenol and DayQuil together is fine." Both contain acetaminophen — combined, they can exceed the 4,000 mg/day limit and cause liver damage, the leading cause of acute liver failure in the US. Consumers think in brands; the danger lives in ingredients.

OnLabel answers OTC medication questions and then verifies its own answer against FDA-grounded ingredient data before showing it to you — flagging active-ingredient duplication and dose ceilings that generic LLMs miss.

⚠️ Not medical advice. OnLabel is a demo, not a medical device. Always confirm medication decisions with a pharmacist or physician.

How it works

The trust core is deterministic, not an LLM guess:

1. Claude drafts an answer and extracts the products/claims involved.
2. Each product is resolved to its active ingredients (FDA / DailyMed / openFDA).
3. A pure-code verifier builds an ingredient ledger, then checks:
   • Duplication — same active ingredient across multiple products
   • Cumulative dose — combined daily total vs. the OTC maximum
   • Class overlap — multiple NSAIDs, decongestants, or sedating antihistamines
4. Each claim is returned with a verdict — ✅ / ⚠️ / 🚫 — and its FDA source.

Because the verdict comes from ingredient composition + arithmetic, OnLabel can actually prove a generic answer wrong.

Scope (v1)

US OTC analgesics and cold/flu products — ingredient duplication and dosing. Prescription-drug interactions are intentionally out of scope (see backlog.md).

Stack

Next.js (App Router) · Claude Agent SDK · TypeScript · Tailwind · Vercel.

Develop

npm install
cp .env.example .env   # add your ANTHROPIC_API_KEY
npm run dev            # app
npm test               # verifier smoke tests
npm run typecheck

Deploy & extend

• Deploy to Vercel (real-device testing): DEPLOY.md — GitHub→Vercel import, ANTHROPIC_API_KEY env var, URL protection, and the first-deploy check that the Agent SDK runs in the serverless function.
• Add a product or ingredient to the KB: docs/ADD-PRODUCT.md — the deterministic extract → verify → gate workflow (no hand-typed clinical numbers). See also docs/EXTRACTION-RULES.md.

Data sources

openFDA drug label & NDC · DailyMed · RxNorm/RxNav · RxClass — all free, public, US government data. See data/otc-knowledge-base.md.

License

MIT — see LICENSE.