CDI vs Drugs.com vs WebMD vs Medscape:
Why the Data Source Is Everything
Most drug interaction checkers — including Drugs.com and WebMD — source their interaction data from Multum, a proprietary third-party database that paraphrases and summarises drug warnings written by someone else. CDI is different: every interaction result is drawn from the verbatim FDA-approved drug label and NIH National Library of Medicine data — the original primary source, not an interpretation of it. On top of that, CDI checks up to 20 drugs simultaneously, surfaces a fourth severity tier (Contraindicated) that most tools omit, offers camera label scanning, shows clean results with no ads inside the findings, and requires no account. It is the only free drug interaction checker built from the ground up for patients and caregivers rather than retrofitted for them.
The Problem With Multum-Based Checkers
⚠ What competitors show you
“Taking warfarin with ibuprofen may increase your risk of bleeding. Monitor for signs of bleeding. Talk to your doctor.”
Source: Multum editorial team. Original FDA document not linked.
✓ What CDI shows you
“NSAIDs, including ibuprofen, may enhance the anticoagulant effect of warfarin and increase the risk of serious, potentially fatal bleeding… patients should be monitored closely when NSAIDs are introduced or discontinued.”
Source: FDA-approved warfarin drug label via openFDA. Full label linked.
The difference is not cosmetic. The FDA-approved label is the legal, authoritative document that drug manufacturers are required to provide. It contains the specific language regulators reviewed and approved as accurate. A Multum summary is a secondary interpretation — useful, but one step removed from the primary source. When a patient or pharmacist needs to know exactly what the FDA has determined about a drug interaction, the label is the answer. CDI is the only free tool that surfaces that answer directly.
Full Feature Comparison
✓ = supported · ✗ = not available · Shaded rows are the features that matter most.
| Feature | CDI FDA primary source | Drugs.com | WebMD | Medscape | Epocrates |
|---|---|---|---|---|---|
★Interaction data source Where the underlying interaction information comes from | Verbatim FDA drug labeling (openFDA) + NIH NLM | Multum — proprietary 3rd-party database | Multum — proprietary 3rd-party database | Proprietary clinical database | Proprietary clinical database |
★Verbatim FDA label language in results Results show the actual words from the FDA-approved drug label — not a paraphrase | ✓ | ✗ | ✗ | ✗ | ✗ |
★Can you verify the source? Each result links back to the original FDA document | ✓ | ✗ | ✗ | ✗ | ✗ |
FDA labels indexed Total drug labels parsed for interaction data | 257,000+ | Undisclosed | Undisclosed | Undisclosed | Undisclosed |
Interaction pairs in database Unique drug-pair interactions on record | 22,184 (published) | Undisclosed | Undisclosed | Undisclosed | Undisclosed |
Drugs checked simultaneously Maximum medications in a single check | Up to 20 | Up to 30 | Up to 30 | 2 at a time | 2 at a time |
Severity levels Granularity of interaction classification | 4 — Contraindicated / Major / Moderate / Minor | 3 — Major / Moderate / Minor | 3 — Major / Moderate / Minor | 3 levels | 3 levels |
Most dangerous interactions shown first Results ranked by severity, not alphabetically | ✓ | ✗ | ✗ | ✓ | ✗ |
★Ads embedded inside interaction results Advertising placed within the actual drug interaction findings | ✓ | ✓ | ✓ | ✗ | ✗ |
★Paywall or premium tier required Some or all results locked behind a subscription | ✓ | ✗ | ✗ | ✗ | ✓ |
★Account required Must sign up before using the tool | ✓ | ✗ | ✗ | ✓ | ✓ |
★Camera label scan (OCR) Point phone at pill bottle to add a drug — no typing | ✓ | ✗ | ✗ | ✗ | ✗ |
Instant drug name autocomplete Resolves brand names, generics, and combinations | ✓ | ✓ | ✓ | ✓ | ✓ |
Shareable results URL One link shares your exact drug list and results with a doctor | ✓ | ✗ | ✗ | ✗ | ✗ |
Designed for patients & caregivers Primary audience is patients and family caregivers, not clinicians | ✓ | ✗ | ✗ | ✗ | ✗ |
Mobile-optimized web experience Works on any phone browser without downloading an app | ✓ | ✓ | ✓ | ✓ | ✗ |
Cost Price for full access | Free | Free | Free | Free (account req.) | Subscription |
★ Starred rows are key differentiators. Based on publicly tested features as of May 2026. Competitor data sourcing verified against published documentation and direct testing.
Built for Patients. Not Retrofitted for Them.
Drugs.com and WebMD were built as drug encyclopedias. Their interaction checkers were added later. CDI was designed from day one around a single question: what does a patient on five medications actually need to know?
Camera label scan
Point your phone at a pill bottle. CDI reads the drug name using AI vision — no typing required. No other free web checker has this. Critical for elderly patients and caregivers managing someone else's medications.
Contraindicated as its own tier
Most tools use three severity levels. CDI adds a fourth — Contraindicated — for combinations the FDA explicitly prohibits. These surface first, above the noise of dozens of moderate interactions.
Shareable results
Your drug list is encoded in the URL. Send one link to your pharmacist or doctor and they see exactly what you see — severity-ranked, FDA-sourced, with no account login required on their end.
No ads inside results
CDI uses AdSense in non-intrusive placements. The interaction findings themselves are clean — no sponsored content, no upsell prompts, no "upgrade to see full results" buried in the list.
Readable at any age
Larger base font size, high-contrast severity colors, plain language. Designed so an 80-year-old can read results without squinting — not an afterthought.
Instant autocomplete, 20 drugs
Resolves brand names, generics, and combination drugs as you type. Add up to 20 medications. Every possible pair is checked simultaneously — nothing slips through a complex regimen.
The Honest Verdict on Each Tool
Each tool has a genuine strength. Here is where each one belongs — and where it falls short.
The only free checker using verbatim FDA and NIH label text. Designed from scratch for patients and caregivers managing complex medication lists. Camera scan, shareable results, clean UI, no account, no paywall, no ads in findings. The right choice for anyone who wants to know exactly what the FDA says.
Excellent encyclopedic resource for learning about individual drugs, side effects, and dosing. Interaction checker uses Multum (paraphrased summaries), lacks FDA label linking, and embeds ads within results. Adequate for a quick two-drug check; not ideal for complex regimens or when you need primary-source accuracy.
High brand recognition. The interaction checker is functional but relies on the same Multum data as Drugs.com, embeds ads inside results, and offers no mechanism to verify where warnings originate. Fine for a casual check; not appropriate when the answer matters.
Strong clinical depth and pharmacokinetic detail. Requires account creation. Written for physicians and pharmacists — language and framing assume clinical training. A good professional reference tool; a poor fit for patients trying to understand their own medications.
Mobile-first, subscription-based clinical decision support. Designed for point-of-care use by providers. Full features require payment. Not intended for patients.
About This Comparison
Competitor data sourcing was verified against each tool’s published documentation, about pages, and direct testing. Drugs.com and WebMD both publicly disclose their use of the Multum database. Competitor interaction pair counts and indexed label totals are not publicly disclosed by any tool except CDI — where undisclosed, this is stated explicitly. CDI’s figures (22,184 pairs, 257,000+ FDA labels) derive from our own database built from the openFDA drug labeling dataset and the NIH National Library of Medicine. We have no commercial relationship with any tool listed here. See our full methodology.
Check Your Medications — With the Primary Source
Enter up to 20 drugs. Get severity-ranked results from verbatim FDA label data in seconds. No account. No ads in your results. No paraphrase.
Check My Medications →Free · No account · Verbatim FDA + NIH data