You are restricted to 3.6 grams of pseudoephedrine base per day.
To put these limits in perspective, 9 grams is roughly equivalent to of standard Sudafed. If you are using a 12-hour or 24-hour formulation, you may reach this limit faster than you expect. when can i buy sudafed again
Legal Requirements for the Sale and Purchase of Drug ... - FDA You are restricted to 3