Unfair competition refers to enterprise uses improper or unfair means to increase the market share of its products, creating an unfair market environment for competitors that produce similar products, and seriously harming the interests of its competitors.
By definition, both Company A and Company B produce weight-loss drugs. In order to expand market share and increase sales profits, Company A made a big publicity on TV stations and some newspapers, pointing out the shortcomings and side effects of Company B's drugs, causing consumers to refuse to buy Company B's products is not unfair competition.