Pseudoephedrine interactions to avoid

Drug interactions | Other interactions | Avoiding interactions | When to see a doctor

Pseudoephedrine is a nasal decongestant and the active ingredient in the brand-name drug Sudafed. It is taken by mouth to treat a stuffy nose associated with colds, allergies, hay fever, sinus congestion, and pressure. It is not an antibiotic and does not treat bacterial infections; however, it may reduce some associated symptoms. 

Pseudoephedrine is available in several formulations, such as immediate-release tablets, extended-release tablets, and liquid (version for children). Pseudoephedrine is available as a single-ingredient product and in various cough and cold medicine types. This article will focus on the single ingredient product.

Because pseudoephedrine can be used to make methamphetamine, medications that contain this drug are sold “behind the counter.” Most states do not require a prescription for pseudoephedrine, but people who want to purchase it must ask the pharmacy staff for the product, which is kept behind the pharmacy counter. Other limitations vary by state, such as the amount of pseudoephedrine a person can buy each month or how old you have to be to purchase pseudoephedrine.

Some of the most common side effects of this medication include:

• Nausea
• Vomiting
• Weakness
• Headache
• Restlessness

Some of the most serious side effects of pseudoephedrine include dizziness, trouble sleeping, stomach pain, difficulty breathing, or a fast, pounding, or irregular heartbeat. Signs of an allergic reaction may include hives, difficulty swallowing or breathing, or swelling of the face, lips, tongue, or throat. If you have any of these symptoms, immediately get emergency medical attention. This is a partial list of side effects, and others may occur. Ask your healthcare provider for a complete list of possible side effects associated with the use of pseudoephedrine. 

Pseudoephedrine interacts with various drugs, including monoamine oxidase inhibitors (MAOIs or MAO inhibitors), tricyclic antidepressants, phentermine, and others. For those who take pseudoephedrine, it’s important to be aware of possible interactions that can cause potential complications.

Pseudoephedrine drug interactions

Pseudoephedrine (PSE) interacts with various drugs and classes of drugs, which can result in different complications. Note that when pseudoephedrine should not be taken with a certain drug, you can check with your healthcare provider or pharmacist to help you find a more appropriate drug. You can also try other methods to relieve a stuffy nose, such as using nasal saline sprays, neti pot rinses, or running a cool-mist humidifier. 

Monoamine oxidase inhibitors (MAOIs)

Monoamine oxidase inhibitors (MAOIs) are a group of older medications that treat depression and other neurological conditions like Parkinson’s disease. 

MAOIs are no longer the first choice in treating depression because there are dietary restrictions, potentially serious side effects, and many drug interactions associated with them. 

Both pseudoephedrine and MAOIs can increase the heart rate and blood pressure. 

When pseudoephedrine is combined with an MAOI, the result can be severely high blood pressure (hypertension), hypertensive crisis (a medical emergency where there is a sudden and severe increase in blood pressure, which could lead to a heart attack or stroke), and a slowed heart rate. At least 14 days should elapse between taking pseudoephedrine and an MAOI. If you take an MAOI, you should not take pseudoephedrine. Consult your healthcare provider for medical advice. 

Examples of MAOIs include the following medicines:

• Azilect (rasagiline)
• Nardil (phenelzine)
• Parnate (tranylcypromine) 

This drug class also includes Zyvox (linezolid), the only antibiotic classified as an MAOI. 

Tricyclic antidepressants

Tricyclic antidepressants (TCAs) are a group of antidepressant medications that include drugs such as Elavil (amitriptyline) and Pamelor (nortriptyline). TCAs should not be combined with PSE. This is because their combined effect could result in high blood pressure and irregular heartbeat. If you take a TCA, you should not take pseudoephedrine. Consult your healthcare professional for medical advice.

Ergots

Ergot medications, sometimes used for migraine, should not be combined with pseudoephedrine. The combination could result in vasoconstriction (narrowing of blood vessels, which slows blood flow) and increased blood pressure. Examples of ergots include:

• Drugs containing ergotamine such as Migergot (ergotamine/caffeine)
• Migranal (dihydroergotamine) nasal spray

If you take an ergot medication, you should not take pseudoephedrine. Consult your healthcare provider for medical advice.

Caffeine

Combining caffeine with pseudoephedrine can increase body temperature and high blood sugar. Caffeine can also intensify certain side effects of pseudoephedrine, like nervousness, shaking, trouble sleeping, and irritability. Caffeine products may include:

• Dietary caffeine, such as in coffee, tea, energy drinks, and others
• Caffeine found in prescription medications such as Fioricet or OTC medications (nonprescription products) like Excedrin Migraine
• Caffeine found in supplements, such as alertness aids like Vivarin and NoDoz

While taking pseudoephedrine, you should avoid caffeine or limit consumption. 

Phentermine

Phentermine, also known by the brand name Adipex-P, is a prescription weight-loss medication. Combining pseudoephedrine and phentermine can lead to increased blood pressure and heart rate. If you take phentermine, ask your healthcare provider about an alternative to pseudoephedrine and try some non-medicinal methods to relieve your cold symptoms. 

Phenylephrine 

Phenylephrine, like pseudoephedrine, is an oral medication used for nasal congestion. Because it is not used to make methamphetamine, it can be found over-the-counter (rather than behind the counter) in products such as Sudafed-PE and many combination cough and cold medications. Recently, this medication has been in the news for being ineffective (although not dangerous). Pseudoephedrine and phenylephrine are similar and should not be used together, not only because they have the same use but also because the combination could cause narrowing of blood vessels and increased blood pressure. 

Other pseudoephedrine interactions

In addition to drug interactions, certain health conditions are not compatible with pseudoephedrine.

Pseudoephedrine and certain medical conditions

Pseudoephedrine is not safe for everyone to take. General contraindications of pseudoephedrine (situations where you should not take this medication) include people who:

• Are allergic to pseudoephedrine or any ingredient in the medication
• Have high blood pressure
• Have coronary artery disease
• Have liver disease
• Have kidney disease
• Have hyperthyroidism (overactive thyroid)
• Have narrow-angle glaucoma
• Have benign prostatic hyperplasia (BPH)
• Have diabetes
• Have taken an MAOI in the past 14 days
• Are you pregnant or breastfeeding

However, in some cases, a healthcare provider may give the green light for a short course of pseudoephedrine if no other options are available. For example, a healthcare provider may recommend a low dose of pseudoephedrine for a short period for an individual with high blood pressure that is well-controlled. 

How to minimize pseudoephedrine interactions

Although pseudoephedrine has some potential interactions, in many cases, it can still be taken safely with some precautions. 

Before beginning a new medicine, consult your healthcare provider for more information and medical advice. Before you start taking pseudoephedrine, make your provider aware of all of your medical conditions, especially if you: 

• Are pregnant or trying to become pregnant
• Are breastfeeding 
• Have diabetes
• Have glaucoma
• Have heart disease
• Have high blood pressure
• Have prostate problems
• Have kidney problems or trouble urinating
• Take an MAOI
• Have thyroid problems
• Have had an unusual or allergic reaction to pseudoephedrine

Tell your physician about all your medicines, including prescription drugs, OTC drugs, vitamins, supplements, or herbal products. While taking pseudoephedrine, do not start any new medication unless approved by your healthcare provider.

It’s also important to note that extended-release pseudoephedrine tablets (long-acting tablets) should not be used in anyone less than 12 years of age. Older people may be more sensitive to the adverse effects of pseudoephedrine and may require lower doses. Always follow the dosage directions on the label and ask a healthcare provider or pharmacist if you have questions about the appropriate dose. The best way to measure liquid medication is to use a medicinal measuring device, as household measuring devices are not as accurate.

When to talk to a healthcare provider about pseudoephedrine interactions

This article outlines various pseudoephedrine interactions but lacks a complete list of every possible interaction. Tell your healthcare provider about all your medical conditions and medicines, including prescription medications, over-the-counter (OTC) drugs, vitamins, and dietary supplements. Doing so helps ensure proper management and monitoring of your medical condition.