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There are legal restrictions on the purchase of medications containing pseudoephedrine and ephedrine due to their potential use in the illicit production of methamphetamine, but these restrictions do not apply to Advil (ibuprofen) [2]. As for ibuprofen, including Advil, the FDA does not have specific limits on the amount that can be purchased at once, but it is recommended to follow the dosing instructions on the label and consult a healthcare provider if you have concerns about the amount you are taking [3]. It is essential to use medications responsibly and avoid exceeding the recommended dosage to prevent potential side effects or adverse reactions.

Sources:
[2]: https://www.fda.gov/drugs/information-drug-class/legal-requirements-sale-and-purchase-drug-products-containing-pseudoephedrine-ephedrine-and
[3]: https://www.goodrx.com/ibuprofen/how-much-is-too-much-advil-ibuprofen