Promethazine for Sleep: Does It Work?

Promethazine is a popular antihistamine used to treat certain allergies. But one of its other notable features is that it causes many users to feel drowsy. For this reason, Promethazine is sometimes used as a sleep aid.

If you’re suffering from either acute or chronic insomnia or simply need a little help getting to sleep on occasion, you may be wondering if Promethazine is a safe, viable option for helping you fall and stay asleep. You’ve come to the right place.

In this article, we’ll explore how Promethazine works as both an allergy medication and a sleep aid so you can make a safe, informed decision about your health.


What is Promethazine?

Promethazine is an antihistamine medication used to relieve allergy symptoms. Similar to Benadryl, Promethazine is known as a sedating antihistamine, which means it’s likely to make you feel drowsy and tired.

While the main purpose of this medication is to treat allergies including hives and hay fever, it’s also proven effective in treating short-term insomnia. In most situations, Promethazine works to treat symptoms like itching or coughing which may keep you up at night. Other uses include treating motion sickness or vertigo and easing other cold symptoms like sneezing and runny nose.

Promethazine sometimes goes by other names including Sominex, Avomine, and Phenergan. You can take this medicine in various forms including liquid, tablets, or capsules, depending on your preference and age. Promethazine can also be combined with other medications designed to treat pain and severe cough. These include dextromethorphan, pholcodine, pseudoephedrine, and paracetamol. It’s also the active ingredient in the OTC cold-and-flu medicine Night Nurse. The type of Promethazine you take is often based on your symptoms and the medicine’s intended use.

How Does Promethazine Work?

Similar to other antihistamines, Promethazine works by blocking chemicals known as histamines from entering your body. Histamines are most commonly associated with allergies including rash and hay ever but also play an important role in regulating your body’s sleep-wake cycle. According to research, histamines create feelings of alertness and vigilance when you’re awake.

By blocking this chemical, people taking Promethazine and other antihistamines tend to feel more relaxed and drowsy, and less alert. It may become easier to fall asleep and you may find yourself sleeping deeper and for longer periods of time. For this reason, Promethazine is sometimes prescribed to treat insomnia. Studies show that this drug helps reduce the number of times a person wakes up at night, improves sleep quality, and increases overall sleep duration.

How to Take Promethazine for Sleep

Your doctor will instruct you on exactly how to take Promethazine. This medicine should be taken on an as-needed basis. If you’re having trouble sleeping or cold and flu symptoms are keeping you up at night, Promethazine can make it easier to fall asleep while also reducing the allergy symptoms that are disrupting your sleep.

Promethazine comes in different forms and dosages depending on your age, weight, and symptoms. The most common strength of this medication is a 25 mg tablet. There are also 10 mg tablets available for children and those who need a lower dose or 50 mg for those who would normally take two 25 mg tablets.

Don’t chew or break up Promethazine tablets. Instead, swallow them whole with a glass of water. This increases the likelihood that your body will absorb all of the medication. Don’t combine Promethazine and alcohol or you may see an increase in the intensity of its side effects (more on these below). Never double your dose or take more than is recommended by your doctor.

When taking Promethazine for sleep or to ease cold and flu symptoms that make it difficult to sleep, it’s suggested you take it approximately 30 minutes before bed. It takes about this long for the drug to make you feel sleepy.

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Promethazine Dosage and Strength Guidelines

Depending on why you’re taking Promethazine, you may need a higher dosage more often. In some cases, PromethaIne works immediately to treat certain conditions including motion sickness. Here are a few more guidelines on how and when to take Promethazine depending on its intended use.

  • 10 mg twice a day or 20 mg three times a day for hayfever or hives
  • 20 mg to 50 mg at night for short-term insomnia
  • 25 mg between one and two hours before an event to prevent motion sickness or 25 mg the night before
  • 25 mg immediately to stop motion sickness followed by another 25 mg that night if you’re still experiencing symptoms
  • 25 mg up to four times a day to treat vertigo

It’s important to note that liquid Promethazine only contains 5 mg of the medication per 5 mL dose. Therefore, pills and capsules are more effective and practical for adults, whereas lower doses in liquid form may be more suitable for children. Consult with your child’s doctor before using Promethazine for any of the above-mentioned reasons.

Side Effects of Promethazine

No medication is without side effects. Whether you’re taking Promethazine for sleep or for allergies, these are some of the most common side effects you may experience.

  • Daytime drowsiness 
  • Dizziness and headaches 
  • Blurred vision 
  • Mental confusion 
  • Nightmares 
  • Dry mouth 
  • Difficulty urinating

There are several ways to combat these side effects so that you can still benefit from the relief Promethazine offers. For example, keep in mind that the drowsiness caused by this medication usually wears off within 12 hours. If possible, avoid driving or operating heavy machinery until these effects wear off. If you feel unsteady on your feet or confused, stop what you’re doing and take a short break until you regain stability. Drink plenty of fluids to prevent headaches, dizziness, and dry mouth. Discuss persistent headaches or nightmares with your doctor.

Other, more serious side effects of Promethazine that need immediate medical attention include:

  • Bruising or bleeding more easily 
  • Yellowing is the skin or whites of the eyes (Jaundice)
  • Unusual face or tongue movements 
  • Stiff joints

Some people are allergic to Promethazine. Signs of an allergic reaction include rash, difficulty breathing, and heart palpitations. If you do experience any alarming side effects call 911 or a friend or family member to drive you to the hospital. You shouldn’t drive while taking Promethazine and experiencing these side effects since the medication is designed to cause sleepiness, which may compromise your driving ability.

Although rare, you can take too much Promethazine and experience severe and serious side effects. These include:

  • Very fast or irregular heartbeat
  • Difficulty breathing
  • Extreme sleepiness that compromises cognitive function and mobility

Children who ingest too much of this drug may also experience:

  • Uncontrolled movements in the hands and feet
  • Moving unsteadily or stumbling
  • Hallucinations
  • Irregular heartbeat

Who Shouldn’t Take Promethazine?

Both as a sleep aid and allergy medicine, Promethazine isn’t for everyone. Some people shouldn’t use this medication or will find themselves at a higher risk of unwanted or dangerous side effects if they do. While in most cases, Promethazine is a highly-effective non-addictive sleep aid, it may negatively interact with other medications or interfere with the treatment of certain health conditions.

If you have any of the following issues, speak with a doctor before trying Promethazine for sleep or to treat allergies and cold or flu symptoms.

  • Problems urinating 
  • Epilepsy 
  • Glaucoma 
  • Pregnant, trying to get pregnant, or breastfeeding 
  • Taking an antidepressant medication such as phenelzine or any other monoamine oxidase inhibitor 
  • Taking any medications that cause dry mouth, make you drowsy, or make it difficult to urinate 
  • Taking opioid painkillers

Promethazine can intensify the side effects associated with these conditions.

Key Facts About Promethazine

Before you turn to Promethazine as a sleep aid, consider these key takeaways.

  • Do not drink alcohol while taking this medication, as it will intensify your drowsiness and other side effects.
  • The liquid form of Promethazine is best for children. 
  • When taking it for sleep, incorporate Promethazine into your nighttime routine and take it at least 30 minutes before bed.
  • Research suggests that Promethazine is a highly-effective, non-addictive way to treat short-term and acute insomnia.
  • Take Promethazine the night before a long trip or 1 to 2 hours before a short trip to prevent motion sickness. 
  • Take Promethazine immediately to treat motion sickness and vertigo. 
  • Common side effects of this medication include headache, dizziness, nightmares, mental confusion, and drowsiness.
  • Promethazine is a common ingredient in other sleep medications including brand names Night Nurse, Day & Night Nurse, and Fedril.

FAQs About Promethazine

If you still have questions regarding Promethazine and how it works as a sleep aid or cold-and-flu treatment, you’re not alone. Here are some FAQs about this OTC medication so you can make an informed decision about your insomnia treatment options.

How Is Promethazine Different From Other Cold-and-Flu Medications?

Promethazine works by blocking a natural chemical in your brain called acetylcholine. This helps ease coughing, congestion, and a runny nose. In some people, it may actually cause a dry nose or dry mouth. This is slightly different than other cold remedies which work to suppress your cough or stop your body from producing phlegm. Instead, Promethazine dries it up. 

How Long Can I Take Promethazine For?

In most cases, Promethazine is intended for short-term use only. It shouldn’t be used as a long-term solution for insomnia or to treat cold-and-flu symptoms, allergies, or vertigo. It can also be taken immediately to treat sudden motion sickness or vertigo, but shouldn’t be your only treatment option. 

Is Promethazine Addictive?

There’s no reason to believe that Promethazine is addictive, however, this is based on the fact that patients should only take this medication in the short term. It is not recommended or approved for long-term use, therefore, there’s no way to know if extended use of this drug could cause addiction or dependency. Individuals who take Promethazine regularly and then abruptly stop may experience dizziness, a racing heart, sweating, trouble sleeping, or an overall sense of feeling unwell or sick. Speak with your doctor about slowly weaning off of this medication.

Does Promethazine Affect Fertility or Contraception?

There’s no evidence to suggest that Promethazine negatively affects fertility in men or women. In addition, this medication shouldn’t interfere with any forms of contraception including the birth control pill or emergency contraceptives. 

Can Lifestyle Changes Work with Promethazine to Help Me Sleep Better?

Research shows that the best and most effective way to treat and prevent both acute and chronic insomnia is to make healthy lifestyle changes. If you’re taking Promethazine for sleep or to ease cold-and-flu or allergy symptoms that are making it difficult to sleep, adopting the following lifestyle changes can only increase the drug’s effectiveness and improve your overall sleep quality. 

  • Set a consistent sleep schedule that consists of going to bed and waking at the same time each day.
  • Create a relaxing sleep environment that includes a quiet, dark, cool bedroom. Invest in quality bedding and a mattress that offers adequate support and comfort.
  • Avoid using digital devices like your phone, laptop, or television too close to bedtime. The blue light from these divides can interfere with your body’s natural ability to feel drowsy and fall asleep.
  • Adopt a relaxing nighttime routine that includes calming activities like reading a book, writing in a journal, meditation, taking a soothing bath, or drinking herbal teas.
  • Avoid stimulants before bed including alcohol (which shouldn’t be taken alongside Promethazine, anyway), nicotine, and caffeine.
  • Avoid taking frequent naps during the day or too late in the day, as these may interfere with your ability to fall asleep at night.
  • Consider natural sleep aids and supplements including melatonin.

Treat the Underlying Cause of Your Insomnia and Enjoy Restorative Sleep

There are numerous causes of insomnia including irregular work schedules, major life events, illness, medications, and stress. Once you identify the underlying cause of your sleep troubles, you can start taking the necessary steps toward overcoming and treating them. If your insomnia is caused by allergies or cold-and-flu symptoms, Promethazine can help. In addition, your doctor may prescribe this medication to treat short-term insomnia thanks to its sleep-inducing side effects.

While Promethazine can help you in the short term, you should have a long-term plan for treating and overcoming your insomnia. The sleep experts at Somnus Therapy utilize the proven benefits of cognitive behavioral therapy for insomnia to help you identify, understand, and overcome your sleep troubles. The convenient online sleep therapy program offers a personalized approach to treating insomnia that you can complete in the comfort of your home and at your own pace.

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“Thanks to Somnus Therapy I now sleep well each night without medication! This was a huge milestone for me – so thank you.”

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