Key takeaways:
Sudafed (pseudoephedrine) is an over-the-counter decongestant that helps relieve nasal and sinus congestion. It’s kept behind the pharmacy counter, but you don’t need a prescription to purchase it.
Common Sudafed side effects include insomnia, headache, and anxiety or restlessness. Dry mouth, tremor, and nausea are also possible.
Serious Sudafed side effects include increased blood pressure and heart rate, confusion or agitation, and increased blood glucose (sugar) levels.
Save on related medications
Sudafed (pseudoephedrine) is an over-the-counter (OTC) medication for nasal and sinus congestion caused by allergies or infections. It works by tightening the blood vessels in your nasal cavity. This lowers blood flow, which in turn helps swelling to go down. It also reduces the amount of mucus in your nose and sinuses.
Sudafed also acts like a stimulant on your brain, and it can activate your body’s “fight or flight” response. Sudafed’s stimulant effects are part of the reason you’ll only find it behind the pharmacy counter. These stimulant effects are also to blame for most Sudafed side effects.
Sudafed side effects at a glance
Here is an overview of common and rare side effects that can occur when taking Sudafed.
Common Sudafed side effects include:
Anxiety or restlessness
Insomnia (trouble sleeping)
Headache
Tremor
Dry mouth
Small increase in blood pressure and heart rate
Nausea
Rare but serious Sudafed side effects and risks include:
Dangerously high blood pressure
Irregular or very fast heart rate
Confusion or agitation
High blood sugar (glucose)
Hallucinations (seeing or hearing things that others don’t)
Allergic reactions
Sudafed’s side effects generally go away on their own once you stop taking it, and you can manage most of them at home. Let’s take a closer look at nine Sudafed side effects and how to manage them.
1. Insomnia
Insomnia is one of the most common Sudafed side effects. It’s caused by Sudafed’s stimulant effects. The best way to avoid insomnia is to avoid taking Sudafed after 6PM (or within a few hours of your normal bedtime).
Your sleep habits should return to normal once you stop taking Sudafed. But improving your overall sleep hygiene may also help. Here are some tips:
Limit caffeine intake, especially before bedtime.
Develop a regular bedtime routine.
Avoid napping during the day.
Avoid screens an hour before bedtime.
Good to know: Sudafed also comes in 12-hour, long-acting formulations. If these forms of Sudafed are interfering with your sleep, a shorter-acting version may be a better choice for you.
2. Headache
Headache is a common side effect of Sudafed. But keep in mind that congestion can cause a headache, too.
If you have a headache while taking Sudafed, an OTC pain reliever, such as acetaminophen (Tylenol) or ibuprofen (Motrin, Advil), can help ease the discomfort. Just make sure a healthcare professional OKs it first. And double-check to make sure any other cold or allergy medication you’re taking doesn’t already include them.
Some home remedies, such as saline nasal rinses (neti pot) or a warm compress on your face, may also help relieve a headache caused by sinus pressure.
Sinus pressure relief: Here are some home remedies and medications that can help treat sinus pain and congestion.
How long does Sudafed stay in your system? Read a pharmacist’s answers to this and more Sudafed (pseudoephedrine) FAQs.
Is it allergies or a cold? Unsure what’s causing your stuffy nose? Learn how to tell the difference between a cold and allergies.
Sudafed dosages: Unsure how much Sudafed is safe to take? Review the recommended dosages to avoid taking more than recommended.
If your headache worsens or doesn’t improve after you stop taking Sudafed, talk to your healthcare team. They’ll make sure there isn’t something else causing it that needs treatment.
3. Anxiety
Sudafed can cause feelings of anxiety or nervousness for some people. It can also make you feel more restless or on edge than usual. This is due to Sudafed’s stimulant effect.
These feelings should go away as Sudafed wears off. And they’ll usually stop once you aren’t taking Sudafed anymore. In the meantime, try relaxing techniques such as coloring, yoga, or listening to music to help calm your mind.
If anxiety or feelings of restlessness are bothersome, try taking a lower dose of Sudafed. Or consider medication alternatives, such as a neti pot, for congestion. If anxiety persists after you stop taking Sudafed, talk to a healthcare professional.
4. Dry mouth and nose
Sudafed can cause dryness in your mouth, throat, and nose. A saline nasal spray can help keep your nasal passages moist. There are also ways to manage dry mouth, including:
Avoiding caffeinated or alcoholic drinks
Staying hydrated
Sucking on ice chips
Chewing on sugarless gum
Using a saliva substitute spray or mouthwash, such as Biotene
Mouth and nose dryness should go away after you stop taking Sudafed. If it doesn’t, it’s best to seek medical care to determine the cause.
5. Tremor
Because Sudafed has stimulant effects, it can sometimes cause muscle tremors or shakiness. This may seem alarming, but usually isn't anything to worry about. The shaky feeling should go away as Sudafed wears off.
Muscle tremors can also be caused by low blood sugar or dehydration. This may be more likely if you’re sick and experiencing low appetite, diarrhea, and/or vomiting. So be sure you’re staying hydrated and eating regularly. It’s also a good idea to limit caffeine, as it’s also a stimulant and can worsen tremors.
If your tremors worsen or don’t go away after you stop taking Sudafed, you should see a healthcare professional.
6. Nausea
Like many medications, Sudafed can cause nausea. While uncomfortable, there are ways to manage it, including:
Taking Sudafed with a small snack
Choosing bland foods, such as saltine crackers or bananas
Staying hydrated by drinking plenty of water or electrolyte drinks
Try a lower dose of Sudafed if nausea becomes bothersome. If nausea persists, or you begin vomiting, it’s best to seek medical care.
7. Changes to heart rate and blood pressure
Sudafed may cause a rise in your blood pressure and heart rate. The higher the Sudafed dose, the more likely it is that this may happen. Immediate-release forms may cause this side effect more often than extended-release forms.
In most cases, increases in your blood pressure and heart rate are small and not a major concern. But in rare cases, Sudafed can also cause life-threatening changes in your blood pressure and heart rate. You’re at a greater risk for this if you take Sudafed in combination with certain other medications, including:
Appetite suppressants, such as phentermine (Adipex-P, Lomaira)
Monoamine oxidase inhibitors, such as selegiline (Emsam, Eldepryl) or phenelzine (Nardil)
Tricyclic antidepressants, such as amitriptyline
Linezolid (Zyvox)
If you have a history of high blood pressure or heart disease, check with your healthcare team first before taking Sudafed.
If you experience chest pain, dizziness, or shortness of breath while taking Sudafed, seek medical care right away.
8. Confusion or agitation
You may experience confusion or agitation while taking Sudafed. In some cases, you may also experience hallucinations. These aren’t common Sudafed side effects and may be more likely in children, especially with high doses.
These symptoms can also be a sign you’ve taken too much Sudafed. Many OTC cold medications, such as Mucinex D (guaifenesin / pseudoephedrine) and Advil Cold and Sinus (ibuprofen / pseudoephedrine), contain the same ingredient as Sudafed. So you may not realize you’re taking extra. One easy way to avoid taking too much Sudafed is by looking out for cold or allergy medications with a “D” in the name. This is a likely indication that the product contains pseudoephedrine, the decongestant in Sudafed.
Be sure to check with your pediatrician or pharmacist about the correct Sudafed dosage. If you or your child experience confusion or other unusual behaviour while taking Sudafed, it’s best to stop the medication and seek medical care.
9. High blood sugar levels
As mentioned, Sudafed can trigger your body’s “fight or flight” response. This response can also cause your blood sugar levels to go up. In most cases, this won’t cause any serious issues. But If you’re living with diabetes, it can be a problem.
Check with your healthcare team before taking Sudafed if you’re living with diabetes. They may recommend you check your blood sugar levels more often while taking it. Or they may suggest a different congestion treatment.
Frequently asked questions
No, Sudafed doesn’t cause drowsiness. In fact, it typically has the opposite effect. Sudafed is more likely to cause feelings of restlessness and make it harder to fall asleep. So it’s best to avoid taking it close to bedtime.
Sudafed can be used to make illegal methamphetamines, an illegal drug. Because of this, in 2006 the FDA mandated that Sudafed be kept behind the pharmacy counter. There are also strict limits on how much pseudoephedrine you can purchase per day and month, and you need a photo ID for purchase. This applies to all products that contain pseudoephedrine, not just Sudafed.
Yes, Sudafed is considered a safe medication for most people if taken as directed. But you should talk to a healthcare professional first if you have a heart condition, diabetes, or thyroid problems. You should also review your medication list with a pharmacist to make sure there aren’t any interactions with Sudafed. And even though it’s sold OTC, Sudafed does have a potential for misuse. So it may not be the best option if you have a history of substance use disorder.
For immediate-release Sudafed, most side effects should resolve about 4 to 6 hours after you stop taking it. Side effects from extended-release formulations can last longer. If side effects worsen or don’t improve after stopping Sudafed, it’s best to reach out to a healthcare professional. But for severe side effects, such as chest pain or trouble breathing, seek emergency care. Don’t wait to see if they improve as Sudafed wears off.
No, Sudafed doesn’t cause drowsiness. In fact, it typically has the opposite effect. Sudafed is more likely to cause feelings of restlessness and make it harder to fall asleep. So it’s best to avoid taking it close to bedtime.
Sudafed can be used to make illegal methamphetamines, an illegal drug. Because of this, in 2006 the FDA mandated that Sudafed be kept behind the pharmacy counter. There are also strict limits on how much pseudoephedrine you can purchase per day and month, and you need a photo ID for purchase. This applies to all products that contain pseudoephedrine, not just Sudafed.
Yes, Sudafed is considered a safe medication for most people if taken as directed. But you should talk to a healthcare professional first if you have a heart condition, diabetes, or thyroid problems. You should also review your medication list with a pharmacist to make sure there aren’t any interactions with Sudafed. And even though it’s sold OTC, Sudafed does have a potential for misuse. So it may not be the best option if you have a history of substance use disorder.
For immediate-release Sudafed, most side effects should resolve about 4 to 6 hours after you stop taking it. Side effects from extended-release formulations can last longer. If side effects worsen or don’t improve after stopping Sudafed, it’s best to reach out to a healthcare professional. But for severe side effects, such as chest pain or trouble breathing, seek emergency care. Don’t wait to see if they improve as Sudafed wears off.
The bottom line
Sudafed (pseudoephedrine) is an over-the-counter medication that helps relieve nasal and sinus congestion. Common Sudafed side effects include insomnia, headache, and anxiety. Dry mouth, tremors, and nausea are also possible.
More serious Sudafed side effects include changes to your blood pressure and heart rate, confusion or agitation, and increased blood sugar (gucose) levels. Generally, side effects will go away after you stop taking Sudafed. But let your healthcare professional know if they continue or worsen after you’ve stopped. And seek emergency care for any side effects that seem life-threatening.
Why trust our experts?
References
Dean, J. S., II, et al. (2023). Alpha-1 receptor agonists. StatPearls.
Głowacka, K., et al. (2021). Pseudoephedrine–benefits and risks. International Journal of Molecular Sciences.
Hilty, D., et al. (2009). Algorithms for the assessment and management of insomnia in primary care. Patient Preference and Adherence.
Kenvue Brands. (2024). Sudafed sinus congestion 12 hour- pseudoephedrine hydrochloride tablet, film coated, extended release [package insert].
MedlinePlus. (2024). Drug-induced tremor.
MedlinePlus. (2025). Pseudoephedrine.
National Institute on Drug Abuse. (2024). Methamphetamine.
Raju, N. N., et al. (2022). Management of medication-induced psychiatric disorders. Indian Journal of Psychiatry.
Salerno, S. M., et al. (2005). Effect of oral pseudoephedrine on blood pressure and heart rate. Archives of Internal Medicine.
U.S. Food and Drug Administration. (2024). Legal requirements for the sale and purchase of drug products containing pseudoephedrine, ephedrine, and phenylpropanolamine.
