Why Taking Antihistamines Is Bad for Sleep

Why Taking Antihistamines Is Bad for Sleep

Taking antihistamines, commonly used to treat allergies, can have adverse effects on sleep. While these medications can provide temporary relief from symptoms like sneezing, itching, and runny nose, they often interfere with the quality and structure of sleep. Understanding the impact of antihistamines on sleep can help you make informed decisions about their use and explore alternative treatments.

Antihistamines are divided into two categories: first-generation and second-generation. First-generation antihistamines, such as diphenhydramine (Benadryl) and doxylamine (Unisom), are known for their sedative effects. These medications cross the blood-brain barrier and bind to histamine receptors in the brain, leading to drowsiness. While this drowsiness might seem beneficial for sleep, it can actually lead to fragmented and poor-quality sleep. A study published in the journal Sleep Medicine found that first-generation antihistamines can decrease REM sleep, the restorative stage of sleep associated with dreaming and memory consolidation.

Second-generation antihistamines, such as loratadine (Claritin) and cetirizine (Zyrtec), are less likely to cause drowsiness because they do not easily cross the blood-brain barrier. However, these medications can still impact sleep indirectly. Research from the Journal of Clinical Sleep Medicine suggests that second-generation antihistamines can cause daytime sleepiness and impair cognitive function, leading to a disrupted sleep-wake cycle.

One of the primary concerns with using antihistamines for sleep is the development of tolerance. Over time, the sedative effects of antihistamines diminish, requiring higher doses to achieve the same effect. This can lead to dependency and exacerbate sleep problems. According to the American Academy of Sleep Medicine, the long-term use of antihistamines for sleep is not recommended due to the potential for tolerance and dependency.

Antihistamines can also cause a range of side effects that negatively impact sleep. Common side effects include dry mouth, blurred vision, constipation, and urinary retention. These side effects can cause discomfort and interrupt sleep. The Mayo Clinic reports that older adults are particularly susceptible to these side effects, which can further complicate sleep issues.

Moreover, antihistamines can interact with other medications, increasing the risk of adverse effects. For instance, combining antihistamines with other central nervous system depressants, such as alcohol or sedatives, can enhance their sedative effects and lead to excessive drowsiness or even respiratory depression. The National Institutes of Health advises against combining antihistamines with other sedatives due to these risks.

Alternative treatments for allergies that do not interfere with sleep include nasal corticosteroids, saline nasal sprays, and lifestyle modifications. Nasal corticosteroids, such as fluticasone (Flonase) and mometasone (Nasonex), effectively reduce inflammation in the nasal passages without causing drowsiness. Saline nasal sprays can help clear nasal congestion and provide relief from allergy symptoms. The American College of Allergy, Asthma & Immunology recommends these treatments as first-line options for managing allergies without disrupting sleep.

Lifestyle modifications can also help manage allergy symptoms and improve sleep quality. Keeping windows closed during high pollen seasons, using air purifiers, and regularly washing bedding can reduce exposure to allergens. Additionally, maintaining a consistent sleep schedule and creating a relaxing bedtime routine can promote better sleep. The Sleep Foundation emphasizes the importance of good sleep hygiene practices for individuals with allergies.

In conclusion, while antihistamines can provide relief from allergy symptoms, they can have detrimental effects on sleep quality and overall health. Understanding the potential risks and exploring alternative treatments can help you manage allergies without compromising your sleep. By prioritizing non-sedating treatments and adopting healthy sleep habits, you can achieve better sleep and improve your overall well-being.


  • Sleep Medicine: "Effects of First-Generation Antihistamines on Sleep"
  • Journal of Clinical Sleep Medicine: "Daytime Sleepiness and Cognitive Impairment from Second-Generation Antihistamines"
  • American Academy of Sleep Medicine: "Risks of Long-Term Antihistamine Use for Sleep"
  • Mayo Clinic: "Side Effects of Antihistamines in Older Adults"
  • National Institutes of Health: "Interactions Between Antihistamines and Other Medications"
  • American College of Allergy, Asthma & Immunology: "Non-Sedating Allergy Treatments"
  • Sleep Foundation: "Sleep Hygiene Practices for Allergy Sufferers"

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before making any changes to your medication or sleep habits.

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