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Table of Contents
Antihistamines and Allergy Relief
What Is Doxylamine?
What Is Diphenhydramine?
Notable Differences
Dosing Guidelines
Side Effects and Safety
Alternative Treatment Options
Frequently Asked Questions
Doxylamine and diphenhydramine are Food and Drug Administration (FDA) approvedantihistaminesused to treatinsomnia,motion sickness,hay fever, andcommon cold symptoms, among other uses.
As commonly used medications, doxylamine and diphenhydramine, administered to adults and children, are available in generic and brand-name forms.
While viewed as similar, doxylamine and diphenhydramine contain notable differences; for example, doxylamine stays in your system longer than diphenhydramine. Therefore, it may be more likely to cause next-daydrowsinessas it takes the body roughly 20 hours to expel the dose.
This article will provide an in-depth comparison of doxylamine and diphenhydramine, reviewing their similarities and differences in uses, dosing requirements, potential side effects, and efficacy.
Getty Images / Milko
The following outlines the role of antihistamines in relieving allergy symptoms, a primary use of doxylamine versus diphenhydramine.
What Are Antihistamines?
Antihistamines temporarily relieve the symptoms ofhay feveror other upper respiratory allergies.
Allergy Symptoms
Allergy symptoms includenasal congestion,redness of the eyes,sneezing,coughing,runny nose, andswollen lymph nodes.
How They Work
Antihistamines bind (also known as their mechanism of action) to histamine receptors on the surface of cells, such as airways and other smooth muscles.
This process blocks the effects of histamines and alleviates allergy symptoms.
Forms of Administration
OTC Antihistamines are typically available as swallowable tablets, capsules, liquid suspensions, nasal sprays, and eye drops.
Conversely, antihistamines can given in prescription form as injectable (intravenous [IV] or intramuscular) medications (administered in healthcare settings).
Examples of common brand-name antihistamines includeZyrtec (cetirizine), Clarinex (desloratadine),Allegra (fexofenadine),Xyzal (levocetirizine), andClaritin (loratadine).
Doxylamine is an orally administered antihistamine used to treat insomnia and allergy symptoms that is approved for use in adults and children 12 years and older.
To treat insomnia, doxylamine is available as an orally administered tablet.
Comparatively, doxylamine is used alongside other medications, such as a liquid and liquid-filled capsule, to treat allergy symptoms.
Doxylamine is often combined with decongestants and other active ingredients, such as acetaminophen and phenylephrine, to relieve allergy symptoms.
Common OTC-branded forms of doxylamine for allergy relief include:
Common OTC-branded forms of doxylamine for the treatment of insomnia include:
Beyond OTC options, prescribed (Rx) doxylamine succinate with pyridoxine, brand-name Bonjesta is approved as a first-line treatment of nausea and vomiting during pregnancy.
Doxylamine, an active ingredient in various products, is available in varying dosage forms, such as extended-release (ER) tablets, immediate-release (IR) tablets, liquid solutions, and liquid-filled capsules.
How It Works
Diphenhydramine is an FDA-approved antihistamine that treats allergy symptoms,eczema,urticaria (hives), andinsect bites.
Age requirements to use diphenhydramine vary depending on the specific branded product used, though generally, diphenhydramine is not encouraged for use in children under 4 years old.
However, an intravenous (IV) injectable form of diphenhydramine is available to treat allergic reactions, especially for people who are unable to take it orally.
OTC Diphenhydramine is available as monotherapy (single-ingredient product) or in combination with other drugs.
Common OTC-branded forms of diphenhydramine for allergy relief include:
Common OTC-branded forms of diphenhydramine for motion sickness include:
Common OTC-branded forms of diphenhydramine for insomnia (diphenhydramine should not be used to cause sleepiness in children younger than 12 years old) include:
Diphenhydramine in Parkinson’s Disease
Diphenhydramine, an active ingredient in various products, is available in multiple oral dosage forms, including tablets, film-coated tablets, rapidly disintegrating (dissolving) tablets, capsules, dissolving strips, powder, and liquid suspension forms.
It is also available as an intramuscular or IV (intravenous, into a vein) injection.
Summary of Notable Differences
Doxylamine and diphenhydramine belong to the same class of drugs and share the exact mechanism of action.
Both are FDA-approved for treating insomnia, hay fever, and allergy symptoms.
Apart from many similarities, however, doxylamine and diphenhydramine carry some notable differences, including the following:
The following outlines standard dosing requirements for using doxylamine and diphenhydramine:
Dosing in Children
Do not use doxylamine and diphenhydramine in children younger than 12 years old for insomnia.
Conversely, do not use these drugs for cough and cold in children younger than 4 years old.
And overall, regardless of use, when administering doxylamine or diphenhydramine to a child under 12 years old, first consult a healthcare provider.
Safe Use Guidance
The following provides suggestions to maximize the safety and efficacy of your prescription while taking doxylamine or diphenhydramine:
Doxylamine and diphenhydramine are considered safe and effective when taken as their respective labels recommend.
However, like all drugs, doxylamine and diphenhydramine carry the potential for side effects.
Therefore, monitor yourself or a loved one closely for the emergence of side effects that worsen or fail to dissipate over time.
Common Side Effects
Common side effects associated with the use of doxylamine and diphenhydramine include:
Diphenhydramine-Specific Side Effects
Severe Side Effects
Some severe side effects of doxylamine and diphenhydramine include:
Use in Older Adults
OTC sleep medications containing diphenhydramine and doxylamine may increase the risk ofliverandkidney dysfunction, drug interactions, worsened side effects events, hangover effects, dizziness, or falls, especially in older adults.
As such, talk to your healthcare provider before taking doxylamine or diphenhydramine if you’re 65 years or older.
When to Avoid
Discuss with your healthcare provider before taking doxylamine and diphenhydramine if you have or have ever had the following conditions:
Potential For Next-Day Drowsiness
Antihistamines, including doxylamine and diphenhydramine, may cause drowsiness.
When taking doxylamine or diphenhydramine for insomnia, plan to achieve a full night’s rest (seven to eight hours) after dosing.
If you get up too soon after taking either medication, you may feel drowsiness or a hangover.
Common alternative cold remedies includezincsupplements,garlic,vitamin C,honey,ginseng, andginger.
Similarly, there are alternatives to medicines to improve sleep patterns in insomnia.
Non-pharmacological therapies include limiting daytime naps, avoiding late-night dinners, and evening intake ofalcohol,caffeine, orsmoking.
It also involves a healthy diet, exercise, regular sleep, and waking time schedules. Meditation or yoga can help to improve the sleeping pattern and reduce underlying anxiety and stress.
Anotherbeneficial therapeutic option in the management of insomnia is cognitive behavioral therapy.
Summary
Doxylamine and diphenhydramine are antihistamine drugs primarily used to relieve symptoms of allergic rhinitis and as a short-term treatment for insomnia.
And while healthcare providers generally view them as similar, they share notable differences.
Doxylamine and diphenhydramine are available in various combination products for their FDA-approved uses.
However, doxylamine and diphenhydramine differ in their dosing potency. Diphenhydramine is usually available in higher doses for the same uses as doxylamine.
Both these drugs can cause drowsiness. It is essential to avoid alcohol when taking these drugs for insomnia.
Ensure how these drugs affect you before doing any activity that requires mental alertness, such as driving and operating machinery.
Frequently Asked QuestionsFor either medication, store away from any location susceptible to high levels of heat or moisture (such as a bathroom) at room temperature (68-77 degrees F).Additionally, if relevant, keep doxylamine or diphenhydramine out of reach of children and pets.Doxylamine and diphenhydramine may improve the symptoms within a week.Call your healthcare provider if symptoms do not improve after seven days.Doxylamine and diphenhydramine start working within 20-30 minutes after oral administration for cold or allergy symptoms.
For either medication, store away from any location susceptible to high levels of heat or moisture (such as a bathroom) at room temperature (68-77 degrees F).Additionally, if relevant, keep doxylamine or diphenhydramine out of reach of children and pets.
For either medication, store away from any location susceptible to high levels of heat or moisture (such as a bathroom) at room temperature (68-77 degrees F).
Additionally, if relevant, keep doxylamine or diphenhydramine out of reach of children and pets.
Doxylamine and diphenhydramine may improve the symptoms within a week.Call your healthcare provider if symptoms do not improve after seven days.
Doxylamine and diphenhydramine may improve the symptoms within a week.
Call your healthcare provider if symptoms do not improve after seven days.
Doxylamine and diphenhydramine start working within 20-30 minutes after oral administration for cold or allergy symptoms.
Correction - September 19, 2024: This article was updated to correct the name of the medication taken with doxylamine for treating nausea and vomiting during pregnancy. It is pyridoxine, not peroxide.
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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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