Every medicine search on MedSideInfo cross-references the sources below. We list them all here, with honest assessments of each one's strengths and limitations, so you can verify our sourcing before you trust the output.
Each source is classified into one of two tiers based on regulatory authority and editorial process. The tier is visible on every result row. Read about our full methodology.
Tier 1 — Official
FDA
fda.govTier 1USBest at: Source-of-truth for US drug approvals, official prescribing information, recall notices, and adverse-event reports.
Weaker at: Pages are written for clinicians and regulatory professionals. Frequency labels are exact but the prose is dense.
NIH
nih.govTier 1USBest at: US government health authority. Anchors most of our official-tier coverage via MedlinePlus + the NLM family.
Weaker at: The .gov family spans many sub-sites; specific drug pages can be reached via MedlinePlus more reliably.
MedlinePlus
medlineplus.govTier 1USBest at: NIH/NLM's consumer-facing drug encyclopedia. Plain-English entries with consistent structure across drugs — easiest US-government source to read.
Weaker at: Coverage of newly-approved drugs trails the FDA label by weeks to months.
NLM
nlm.nih.govTier 1USBest at: US National Library of Medicine — backbone for MedlinePlus, PubMed, and DailyMed. Authoritative regulatory metadata.
Weaker at: Often a redirect surface to its child sites rather than a destination.
NHS
nhs.ukTier 1UKBest at: UK National Health Service. Excellent plain-English drug pages, often with frequency wording that maps cleanly to our buckets.
Weaker at: UK-specific labelling. A drug approved in the US but not the UK may have no NHS page; brand names differ between countries.
PubMed
pubmed.ncbi.nlm.nih.govTier 1GlobalBest at: Primary clinical-literature index. Best place to find numerically-precise adverse-event rates from clinical trials.
Weaker at: Abstracts are written for researchers; rates may be stated as fractions (e.g. "12 of 234 patients") rather than the frequency labels consumer pages use.
PubMed Central
pmc.ncbi.nlm.nih.govTier 1GlobalBest at: Full-text complement to PubMed. When an abstract teases an adverse-event finding, PMC often has the full paper with the complete safety table.
Weaker at: Coverage is partial — not every PubMed paper has a PMC full text.
Tier 2 — Medical
Mayo Clinic
mayoclinic.orgTier 2USBest at: Comprehensive consumer-facing drug pages with clear More-common / Less-common / Rare sub-sections. The closest thing to a default for adult patient education in the US.
Weaker at: Pages are often long and bury the side-effects section under indication / dosing prose; we slice for the section to keep extraction tight.
WebMD
webmd.comTier 2USBest at: Wide drug-coverage breadth. Often the only consumer source that lists a particular brand-name combo product.
Weaker at: Editorial quality varies between articles; we treat WebMD as Tier 2 (Medical) rather than Tier 1 (Official) for this reason.
Drugs.com
drugs.comTier 2USBest at: Indexes the FDA prescribing-information label in a more readable form. Excellent for finding the official frequency tables alongside consumer prose.
Weaker at: US-centric. International labelling differences are not reflected.
RxList
rxlist.comTier 2USBest at: Long-form pharmacology reference. Useful when other sources are thin on a niche drug.
Weaker at: Layout is dense; commercial pages can crowd the editorial sections.
Cleveland Clinic
clevelandclinic.orgTier 2USBest at: Consumer-facing peer to Mayo Clinic. Clean prose. Good when Mayo's page is unusually thin or recently restructured.
Weaker at: Drug coverage is narrower than Mayo or Drugs.com — not every drug has a dedicated page.
Healthline
healthline.comTier 2USBest at: Consumer-friendly tone with editorial medical review. Often discusses side effects in narrative form alongside lifestyle context.
Weaker at: Listicle / SEO-optimized format means the side-effects section may be shallow on commonly-searched drugs.
Medical News Today
medicalnewstoday.comTier 2GlobalBest at: Consumer-health reference with named medical reviewers per article.
Weaker at: News-driven editorial; coverage of older drugs may be thin compared to Mayo or MedlinePlus.
What's missing
We are deliberately conservative about which sources qualify. The list above is not exhaustive — it's the set we trust enough to cross-reference automatically. Sources we have considered but not added yet:
- Patient forums (r/Drugs, MedHelp, etc.): high signal on lived experience but no editorial review; we link to them when a user explicitly chooses to, but we do not extract structured side-effect data from them.
- Pharmaceutical company labels (Pfizer, Merck, etc.): authoritative for their products, but the conflict-of-interest framing makes editorial neutrality complicated. We rely on the FDA-hosted versions of the same labels instead.
- Region-specific regulators outside US / UK (EMA, Health Canada, TGA Australia, CDSCO India): we plan to add these as our user base extends. Today our coverage skews US/UK.
Customize this for yourself
The list above is our default. Your own preferences may be different — maybe you trust the FDA label more than any consumer site, or you want to drop a source you don't find useful, or you want to add a regional regulator we don't cover yet.
Open MedSideInfo and head to the Sources tab to:
- Reorder which sources fill the eight result slots first.
- Move a source between Tier 1 (Official) and Tier 2 (Medical) — your override beats our default.
- Add a new domain we don't already include.
- Hide a source from your own results.
Your customizations apply only to your account. Open the app and click the Sources tab to start.
Want to suggest a source we should add to the default list for everyone? Tell us via the feedback form.