Written by Emilie White, PharmD | Reviewed by Tegan Smedley, PharmD, APh

Updated on July 19, 2024

Key takeaways:

• Sudafed (pseudoephedrine) is an over-the-counter decongestant that helps relieve nasal and sinus congestion. It’s often 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. 
• Rare but serious Sudafed side effects include increased blood pressure and heart rate, confusion or agitation, and increased blood glucose (sugar) levels.

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SudafedPseudoephedrine

Table of contents

Insomnia

Headache

Anxiety

Dry mouth

Tremor

Nausea

Heart-related effects

Confusion

High blood glucose

FAQs

Bottom line

References

nong2/iStock via Getty Images Plus

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 the cause of 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.

EXPERT PICKS: WHAT TO READ NEXT

• 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 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.

Common Sudafed side effects include:

• Anxiety or restlessness
• Insomnia
• Headache
• Tremor
• Dry mouth
• Nausea

Rare but serious Sudafed side effects include:

• High blood pressure
• Increased heart rate
• Confusion or agitation 
• High blood glucose
• Hallucinations
• Abuse or misuse
• Allergic reactions

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Sudafed’s side effects generally go away on their own once you stop taking it, and most can be managed at home. Let’s take a closer look at nine Sudafed side effects and how to manage them.

1. Insomnia

Insomnia (trouble sleeping) 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).

This side effect should go away 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

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Keep in mind that Sudafed also comes in 12-hour and 24-hour 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 spray or a warm compress on your face, may also help relieve a headache caused by sinus pressure.

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

Sudafed can cause dryness in your mouth, throat, and nose. While having a dry mouth is uncomfortable, there are simple ways to manage it, including: 

• Avoiding caffeinated or alcoholic drinks
• Staying hydrated
• Sucking on ice chips
• Chewing on sugarless gum
• Using a saliva substitute spray or mouthwash

Your dry mouth 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 is a stimulant, 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 glucose (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.

Although rare, 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
• Monoamine oxidase inhibitors such as selegiline (Emsam, Eldepryl) or phenelzine (Nardil)
• Tricyclic antidepressants
• 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 (seeing or hearing things that aren’t there). 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 these side effects, it’s best to stop taking Sudafed and seek medical care.

9. High blood glucose levels

As mentioned, Sudafed can trigger your body’s “fight or flight” response. This response can also cause your blood glucose (sugar) levels to go up. In most cases, this won’t cause any issues for you. But If you’re living with diabetes, it can be a problem. 

Check with your healthcare team before taking Sudafed if you have diabetes. They may recommend you check your blood glucose levels more often while taking it. Or they may suggest a different congestion treatment.

Frequently asked questions

Does Sudafed make you drowsy? 

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