How Long Before Bedtime To Take Sudafed

In our latest question and answer, the pharmacist discusses how long before bedtime Sudafed (pseudoephedrine) should be taken to avoid issues with insomnia.


How long before bedtime should I take my last dose of Sudafed? I am taking Sudafed for a cold/flu (Not sure which).  I want to be able to sleep so I was wondering how long Sudafed keeps me awake? What is the half life?

Asked by Richard On Dec 31, 2017

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Jan 04, 2018

Sudafed (pseudoephedrine) is a oral nasal decongestant that is used to treat nasal congestion due to the common cold and allergies. It is also helpful relieving congestion of the eustachian (i.e. auditory) tubes in the ears. Sudafed works by producing vasoconstriction, shrinking swollen nasal membranes and opening nasal passages to ease airflow. It can also facilitate the drainage of sinus secretions.

Sudafed is classified as a sympathomimetic and has mild stimulatory effects. As such, it is recommended to avoid taking before bedtime as it can cause insomnia, trouble sleeping and a general feeling of awakeness. Below are the commonly reported central nervous system effects:

  • Restlessness
  • Headache
  • Lightheadedness
  • Dizziness
  • Insomnia

Data indicates that both children and the elderly are more susceptible to the stimulating effects of Sudafed than adults.

There are a variety of Sudafed products available and administration recommendations vary per product. Available Sudafed products include:

  • Sudafed (Immediate Release)
  • Sudafed 12 Hour
  • Sudafed 24 Hour
  • Sudafed PE (family of products)

Sudafed Timing Before Bedtime Recommendations

Sudafed (Pseudoephedrine) Immediate Release Products

Studies show that after taking immediate release Sudafed products by mouth, the effects begin within 30 minutes. The duration of action can vary depending on the person but generally last around four to six hours. The half life of Sudafed is reported to be anywhere from 9-16 hours but can vary.

Although the nasal decongestant effects of immediate release Sudafed products can last 4-6 hours (with the half life being even longer), the stimulatory effects aren't expected to last that length of time. The manufacturer of Sudafed recommends that the product should be administered at least two hours before bedtime. Some patients may be more sensitive to the stimulatory effects of Sudafed. If this is the case, plan on taking Sudafed at least 6 hours before bedtime

Sudafed (Pseudoephedrine) Extended Release Products

In addition to the immediate release product, Sudafed is also available in 12 and 24 hours formulations. For both, it is recommended to take them as far away from bedtime as possible. The 24 hour formulations should be taken first thing in the morning. Although the nasal decongestant effects will last about one day, the stimulatory effects should subside (if they occur at all), within a few hours. 

The 12 hours product should generally not be dosed within four to six hours of bedtime. Like the 24 hour products, the stimulatory effects shouldn't be an issue if spaced far enough from the time you go to bed.

Sudafed PE (Phenylephrine) Products

Sudafed PE products do not contain the active ingredient pseudoephedrine. They contain phenylephrine, which typically is associated with less stimulatory effects in users. However, the same recommendation is in place in regard to administration. Separate from bedtime by at least 2 hours for immediate release products and longer for extended release products.

To summarize, the following recommendations should be considered when dosing Sudafed in regard to insomnia concerns:

  • Per the manufacturer, dose Sudafed immediate release products at least 2 hours before bedtime to avoid issues with insomnia. Certain individuals may need to take their last dose 4-6 hours before bedtime.
  • Dose extended release products at least 4 to 6 hours before bedtime to avoid issues with insomnia. 

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Office: 716-389-3076

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