The heading's subheading structure gives priority to antibiotic content: a product containing a penicillin or streptomycin derivative falls under 300410 regardless of other ingredients, while non-penicillin antibiotics go to 300420. Hormone-containing products without antibiotics fall under the 300431–300439 group. For complex combinations, consult the HS explanatory notes and consider requesting a CBP binding ruling.

Importers must ensure the foreign manufacturer holds a valid FDA drug establishment registration, and most shipments require prior notice submission. Products subject to DEA scheduling — such as those containing ephedrine or pseudoephedrine — require additional DEA import permits. Working with a licensed customs broker and a regulatory affairs specialist is strongly advisable given the multi-agency compliance layer.

Many pharmaceutical tariff lines originating from China are subject to Section 301 measures. The applicable measure depends on the specific 10-digit HTS line, so importers should check the current Section 301 list and any applicable exclusions before entry.