For standard immediate-release tablets, adults can take 60 mg of pseudoephedrine every four to six hours, up to a maximum of 240 mg in 24 hours. That works out to four doses per day if you space them evenly. Extended-release versions have different schedules, and the formulation you’re using determines how often you should dose.
Dosing by Formulation
Pseudoephedrine comes in three main formulations, each with its own schedule:
- Immediate-release (standard tablets, capsules, liquid): 60 mg every 4 to 6 hours. No more than 240 mg in 24 hours.
- 12-hour extended-release: One tablet every 12 hours. No more than 2 tablets in 24 hours.
- 24-hour extended-release: One tablet per day.
The extended-release versions contain more pseudoephedrine per tablet (typically 120 mg for 12-hour and 240 mg for 24-hour), which is why you take them less frequently. Don’t crush or split extended-release tablets. Doing so releases the full dose at once, which can cause a spike in side effects.
How Long You Can Keep Taking It
Most product labels recommend using pseudoephedrine for no more than seven consecutive days. Beyond that point, ongoing congestion likely signals something that needs a different approach, whether it’s allergies, a sinus infection, or another underlying issue. Prolonged daily use also increases the chance of side effects like elevated blood pressure and sleep disruption.
How Pseudoephedrine Works
Pseudoephedrine narrows the blood vessels in your nasal passages. When you’re congested, the tissue lining your nose and sinuses swells with extra blood flow and fluid. Pseudoephedrine triggers receptors on those blood vessels that cause them to constrict, which reduces the swelling, opens your airways, and helps your sinuses drain. This is why it works for stuffiness but doesn’t do much for a runny nose or sneezing on its own.
Side Effects to Watch For
The same blood-vessel-narrowing effect that clears your nose can show up elsewhere in your body. The most common side effects are insomnia, nervousness, anxiety, and a jittery or restless feeling. Some people notice a faster heartbeat. These effects tend to be more noticeable at higher doses or when you take it later in the day, so timing your last dose well before bedtime helps.
Pseudoephedrine can also raise blood pressure. For most people with normal blood pressure, the increase is small. But a subset of people experience more pronounced spikes, which is why the packaging carries warnings for anyone with high blood pressure, heart disease, thyroid problems, or diabetes. There have been reports over the years of heart attacks, strokes, and abnormal heart rhythms linked to pseudoephedrine use, particularly in people with pre-existing cardiovascular conditions. If you have high blood pressure and still use pseudoephedrine, monitor your blood pressure more frequently while taking it.
Children’s Dosing
Extended-release formulations are not intended for children under 12. For immediate-release forms, children 12 and older follow the adult dosing schedule of 60 mg every four to six hours. Children younger than 12 should only take pseudoephedrine under a doctor’s guidance, as they’re more sensitive to its effects and can experience sedation, agitation, or in rare cases, seizures.
Purchase Limits
Because pseudoephedrine can be used to manufacture methamphetamine, it’s sold from behind the pharmacy counter in the United States, and you’ll need to show ID. Federal law caps purchases at 3.6 grams per day and 9 grams per 30-day period. For context, a standard box of 30 mg tablets contains well under 3.6 grams total, so these limits rarely affect someone buying for personal use. They’re tracked electronically, though, so you may be flagged if you buy from multiple stores in a short window.