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Pseudoephedrine: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on Mar 23, 2020.

1. How it works

  • Pseudoephedrine is a decongestant that constricts (shrinks) dilated blood vessels within the nose, relieving congestion.
  • It causes vasoconstriction by stimulating primarily alpha-adrenergic receptors. It also has weak activity at beta-adrenergic receptors. It is chemically related to ephedrine, but with less central nervous system activity (fewer effects on the brain).
  • Pseudoephedrine belongs to the class of medicines known as nasal decongestants. It may also be called a sympathomimetic.

2. Upsides

  • Significantly more effective as a decongestant than phenylephrine.
  • Tablets, chewable tablets, liquid and nasal preparations of pseudoephedrine effectively treat nasal and sinus congestion; however, the sale of cold and flu products containing pseudoephedrine is limited to behind the counter because pseudoephedrine may be used for the illicit production of methamphetamine.
  • Generic pseudoephedrine is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Sleep disturbances, restlessness, rash or itching, loss of appetite, feeling of warmth or redness under the skin.
  • May not be suitable for some people including those with high blood pressure, heart disease, diabetes, prostatic hyperplasia or urinary obstruction, kidney disease, a seizure disorder, increased ocular pressure or angle-closure glaucoma, or a thyroid disorder. Do not use pseudoephedrine if you are pregnant or breastfeeding unless under a doctor's advice.
  • May interact with some other medications including monoamine oxidase inhibitors, blood pressure medications, beta blockers, and antidepressants.
  • Not suitable for children under four. Always talk with a doctor before giving cough or cold medicines to children.
  • Will cause a false-positive result on a urine test for amphetamines.
  • Individuals purchasing pseudoephedrine must produce photo ID and supply personal information that the store must keep for at least two years. The quantity that can be purchased is also limited.

Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.

4. Bottom Line

Pseudoephedrine effectively relieves nasal and sinus congestion and is found in several behind-the-counter combination cold and flu remedies. Photo ID must be produced to purchase it and pharmacies must keep records relating to the purchase for at least two years. Sleeplessness is a common side effect.

5. Tips

  • Use as directed for short periods of time only (no more than seven days). Pseudoephedrine only provides symptom relief, it does not cure a cold.
  • Take with a full glass of water.
  • Chew the chewable tablet before swallowing. Shake the oral suspension well before measuring out the correct dose. Always use a proper measuring spoon or dropper to ensure you are getting the correct dose. Swallow extended-release capsules whole, do not break open or chew. Note: some tablets may not fully dissolve and the tablet shell may be visible in the stool.
  • Do not give pseudoephedrine to children without talking to a doctor first. Pseudoephedrine must never be given to children under the age of four.
  • Call your doctor if your symptoms have not improved within seven days of treatment, or if you develop a fast, pounding or uneven heartbeat, severe dizziness or anxiety, severe headache, an allergic-type reaction, fever or rash.
  • Talk to your doctor or pharmacist before using any other cold or flu remedies as they may also contain pseudoephedrine or another decongestant.
  • Avoid taking pseudoephedrine if you also take caffeine supplements, diet pills or other stimulants (such as ADHD medications).

6. Response and Effectiveness

  • The decongestant effect of pseudoephedrine is noticeable within 30 minutes of oral administration and reaches a peak within one to two hours. One immediate-release tablet of pseudoephedrine lasts anywhere from three to eight hours.

7. Interactions

Medicines that interact with pseudoephedrine may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with pseudoephedrine. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with pseudoephedrine include:

  • antidepressants, such as amitriptyline, amoxapine, clomipramine, doxepin, imipramine, isocarboxazid, or phenelzine
  • atomoxetine
  • atropine
  • benztropine
  • bromocriptine
  • diabetes medications, such as metformin, glimepiride, glipizide, glyburide, or insulin
  • digoxin
  • duloxetine
  • heart medications, such as atenolol, betaxolol, bisoprolol, carvedilol
  • levodopa
  • linezolid
  • methylene blue
  • methylphenidate
  • migraine medications, such as dihydroergotamine or ergotamine
  • oxybutynin
  • orphenadrine
  • potassium citrate
  • reserpine
  • selegiline
  • venlafaxine.

Note that this list is not all-inclusive and includes only common medications that may interact with pseudoephedrine. You should refer to the prescribing information for pseudoephedrine for a complete list of interactions.


Pseudoephedrine. 07/2019.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use pseudoephedrine only for the indication prescribed.

Copyright 1996-2020 Revision date: March 23, 2020.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.