I usually find drug labels via Google, which may flag the FDA website, or a manufacturer website, or other sources.
The CMS OPPS drug passthrough application referred to drug labeling at a website run by National Library of Medicine, DAILY MED. New to me. Here it is:
https://dailymed.nlm.nih.gov/dailymed/index.cfm
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Update: Two colleagues pointed out there is ALSO a similar, and more historical, database at FDA;
https://www.accessdata.fda.gov/scripts/cder/daf/
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TESTING DAILYMED...
Want Herceptin? They got it.
https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=492dbdb2-077e-4064-bff3-372d6af0a7a2
Want Gozellix, a new prostate cancer PET scan biomarker? They got it.
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https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=abeab169-e38e-433a-b8a9-f1dab31518c8
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And here's the FDA website, which has a long comprehensive arcive of updates to Herceptin's 1998 labeling:
