Final answer:
When pseudoephedrine is obtained via prescription, the standard over-the-counter limits do not typically apply, as prescriptions are monitored separately to prevent abuse and illegal use. Restrictions are mainly for over-the-counter sales to combat methamphetamine production.
Step-by-step explanation:
Pseudoephedrine is a decongestant that is available both over-the-counter and by prescription. When obtained via prescription, the usual limits for over-the-counter purchases may not apply, depending on the rules and regulations of the specific country or state. For instance, in the United States, the Combat Methamphetamine Epidemic Act sets limits on the sale of over-the-counter products containing pseudoephedrine, but these restrictions typically do not apply to prescription quantities, which are monitored by prescription tracking systems to prevent abuse and illegal diversion for the production of methamphetamine.
Pseudoephedrine is also found in many over-the-counter medications in combination with other substances such as antihistamines and anti-inflammatory drugs. The medicinal uses of pseudoephedrine extend to being a stimulant and wakefulness-promoting agent. However, due to its potential for being converted into methamphetamines, its sale is tightly regulated.