Any State
What legal theory allows someone who regularly ingests a powerful drug such as testosterone, and then suffers side effects, to sue the drug manufacturer?
Going with Mnemosyne's idea that this might not be homework or a hypothetical and is a U.S. law-based question, there are three theories of product liability - negligence, breach of warranty, and strict tort liability. You can research these, TomBrooklyn, to see what each involves.
The state matters, however, as states handle these in different ways. There are very few "any state" laws.
A drug manufacturer has several defenses that it could use in any suit brought against it. These include a statute of limitations defense, a statutes of repose defense, an unavoidable danger defense, a federal preemption defense, a failure to mitigate defense, and contributory or intervening or superseding negligence defenses. A misuse of a product (ingesting a topical medicine), which would fall under contributory negligence, can be a complete defense to liability for the manufacturer in some states.
