How do antihistamines cause drowsiness. What are the differences between first-generation and second-generation antihistamines. How can you minimize drowsiness from allergy medications. What should you know about antihistamines in cold and flu medications.

Understanding the Mechanism of Antihistamine-Induced Drowsiness

Antihistamines are commonly used to treat allergies and cold symptoms, but they often come with an unwanted side effect: drowsiness. To understand why this occurs, we need to delve into the role of histamine in our bodies.

Histamine is a chemical produced by the immune system to combat allergens and germs. When the body perceives a threat, such as during an allergic reaction or a cold, histamine production increases. This leads to typical allergy or cold symptoms like runny nose, coughing, sneezing, and itchy eyes.

Interestingly, histamine also plays a crucial role in the brain, helping us stay awake and alert. When antihistamines are taken to alleviate respiratory symptoms, they can cross the blood-brain barrier and interfere with this wakefulness-promoting function, resulting in drowsiness.

The Dual Role of Histamine

• In the immune system: Fights off allergens and germs
• In the brain: Promotes wakefulness

Why do antihistamines cause drowsiness? Antihistamines block the effects of histamine throughout the body, including in the brain. By inhibiting histamine’s wake-promoting effects in the central nervous system, these medications can induce sleepiness as a side effect.

First-Generation vs. Second-Generation Antihistamines: Drowsiness Comparison

Not all antihistamines are created equal when it comes to causing drowsiness. There are two main categories of antihistamines: first-generation and second-generation.

First-Generation Antihistamines

First-generation antihistamines, such as diphenhydramine (Benadryl®), are more likely to cause drowsiness. These medications readily cross the blood-brain barrier and affect histamine receptors in the brain, leading to sedation.

Is there a non-drowsy version of Benadryl®? Currently, there is no non-drowsy Benadryl® available on the market. The sedating effect of diphenhydramine is a key characteristic of this medication.

Second-Generation Antihistamines

Second-generation antihistamines, including cetirizine (Zyrtec®), fexofenadine (Allegra®), and loratadine (Claritin®), are often marketed as “non-sedating” options. These medications are less likely to cross the blood-brain barrier and typically cause less drowsiness compared to their first-generation counterparts.

Which second-generation antihistamine is the least sedating? Among the second-generation antihistamines, Allegra (fexofenadine) is generally considered to be the least sedating option.

Strategies to Minimize Drowsiness from Allergy Medications

If you find yourself struggling with drowsiness from allergy medications, there are several strategies you can employ to minimize this side effect:

1. Opt for second-generation antihistamines
2. Consider nasal spray antihistamines
3. Use intranasal corticosteroids
4. Take antihistamines in the evening
5. Avoid alcohol consumption

How can you reduce drowsiness from allergy medications? One effective approach is to switch to second-generation antihistamines or nasal spray antihistamines, which are less likely to cause sedation. Additionally, using intranasal corticosteroids can help reduce your reliance on antihistamines altogether.

When is the best time to take antihistamines to avoid daytime drowsiness? Taking antihistamines in the evening rather than in the morning can help you avoid daytime drowsiness. The sedating effects may wear off by the next morning, potentially improving your sleep quality as well.

The Role of Antihistamines in Cold and Flu Medications

Many people are unaware that cold and flu medications often contain antihistamines, particularly first-generation ones. These are included because they are effective at treating cold symptoms and reducing runny noses.

Why are first-generation antihistamines commonly found in cold medicines? First-generation antihistamines are often better at treating cold symptoms and drying up runny noses compared to newer types. Their sedating effect is also beneficial for nighttime use, helping patients get rest while managing their symptoms.

Important Considerations for Cold and Flu Medications

• Look for “nighttime” labeling, indicating sedating antihistamines
• Check dosages carefully, as they may vary even within brands
• Avoid combining multi-symptom cold medications with single-ingredient antihistamines

How should you approach taking cold medicines containing antihistamines? It’s crucial to take the labeling seriously, especially for nighttime formulations. Some cold medicines contain highly sedating antihistamines like doxylamine. Always read labels carefully and follow dosage instructions to avoid over-sedation.

Nasal Spray Antihistamines and Intranasal Corticosteroids: Alternative Options

For those seeking alternatives to oral antihistamines, nasal spray antihistamines and intranasal corticosteroids offer potential solutions with a lower risk of systemic side effects.

Nasal Spray Antihistamines

Nasal spray antihistamines target nasal passages directly, reducing the amount of medication that enters the bloodstream. This localized approach can result in fewer systemic side effects, including drowsiness.

Are nasal spray antihistamines available over-the-counter? Most nasal spray antihistamines are available only by prescription. However, they can be an excellent option for those who experience significant drowsiness with oral antihistamines.

Intranasal Corticosteroids

Intranasal corticosteroids are another effective option for managing allergy symptoms, particularly nasal congestion. Regular use of these medications can help reduce reliance on antihistamines.

How long does it take for intranasal corticosteroids to start working? Intranasal corticosteroids typically take a few days to start showing their full effects. It’s important to be patient and consistent with their use. Your doctor may recommend using an antihistamine alongside the corticosteroid for the first few days to manage symptoms while the corticosteroid takes effect.

Smart Use of Allergy Medications: Balancing Efficacy and Side Effects

Effectively managing allergy symptoms while minimizing side effects requires a thoughtful approach to medication use. Here are some key points to consider:

• Know your allergens and take steps to reduce exposure
• Monitor how different medications affect you personally
• Consult with a board-certified allergist for persistent or severe symptoms
• Consider alternative treatment options if side effects are problematic

What should you do if antihistamines are causing significant side effects? If you’re experiencing troublesome side effects from antihistamines or other allergy medications, it’s important to consult with your healthcare provider. They can offer alternative treatment options, such as allergen immunotherapy or non-drowsy allergy medicines, to provide relief without unwanted side effects.

Advanced Treatment Options for Allergy Management

For individuals with severe or persistent allergies, or those who struggle with medication side effects, there are advanced treatment options available.

Allergen Immunotherapy

Allergen immunotherapy, also known as allergy shots or sublingual immunotherapy, is a long-term treatment that can reduce sensitivity to specific allergens. This approach can lead to lasting relief and reduced need for daily medications.

How does allergen immunotherapy work? Allergen immunotherapy involves exposing the body to gradually increasing amounts of an allergen. Over time, this can desensitize the immune system, reducing allergic reactions and symptoms.

Biologic Therapies

For severe allergies or related conditions like asthma, biologic therapies may be an option. These targeted treatments work by interrupting specific pathways in the allergic response.

What types of allergies can be treated with biologic therapies? Biologic therapies are primarily used for severe asthma, chronic hives, and certain types of severe eczema. They can be particularly helpful for patients who don’t respond well to traditional treatments.

The Importance of Personalized Allergy Management

Every individual’s experience with allergies and allergy medications is unique. What works well for one person may cause intolerable side effects for another. This variability underscores the importance of a personalized approach to allergy management.

Factors Influencing Individual Response to Allergy Medications

• Genetic variations in drug metabolism
• Severity and type of allergies
• Presence of other medical conditions
• Interactions with other medications

Why is it important to stick with a medication that works for you? Once you find an antihistamine or other allergy medication that effectively relieves your symptoms without causing significant side effects, it’s generally best to continue with that medication. If you need to switch brands or try a generic version, be sure to check the chemical ingredients and dosages to ensure they match your current effective treatment.

How can you determine the best allergy treatment plan for your needs? Working closely with a healthcare provider, preferably a board-certified allergist, is the best way to develop an effective and personalized allergy management plan. They can help you identify your specific allergens, recommend appropriate medications or treatments, and adjust your plan as needed based on your response and any side effects.

The journey to finding the right allergy medication can be complex, but with patience and careful attention to your body’s responses, it’s possible to achieve effective symptom relief while minimizing unwanted side effects like drowsiness. Remember that allergy management is not just about treating symptoms – it’s also about understanding your triggers, reducing exposure where possible, and considering long-term solutions like immunotherapy when appropriate. By taking a comprehensive and personalized approach to allergy care, you can significantly improve your quality of life and minimize the impact of allergies on your daily activities.

When Allergy or Cold Medication Makes You Drowsy

Tips for Staying Alert

By Purvi Parikh, MD

In treating allergies or a cold with antihistamines, you may experience drowsiness, a common side effect of the medication.

How does this happen? Histamine is a chemical produced by the immune system to fight off allergens and germs. When there is a threat of allergies or infection (such as the common cold), histamine is even more active. In its search-and-destroy process, it can cause allergy or cold symptoms such as runny nose, coughing, sneezing and itch eyes. Antihistamine medications relieve these symptoms by blocking the unwanted effects of histamine.

Unrelated to the immune system, histamine is also produced in the brain, where it plays an important part in feeling awake. Antihistamines used to treat respiratory symptoms can get into the brain and interrupt this work, making you feel drowsy.

What can you do about drowsiness from allergy medicines?

Some antihistamines are less likely to cause drowsiness than others. Reactions vary considerably from one person to another. What relieves your symptoms without making you sleepy may be different from what works for someone else.

When you find one that works for you, stick with it – check chemical ingredients and dosages before changing brands or generics. On the other hand, if one doesn’t work for you, try another type.

Does diphenhydramine (Benadryl®) make you sleepy? First-generation antihistamines such as diphenhydramine (Benadryl®) usually cause drowsiness because they are less likely to affect the histamine produced in the brain or have other unwanted effects in the brain. Currently, there is no non-drowsy Benadryl® on the market.

Non-drowsy allergy medicines do exist. Newer, second-generation antihistamines such as cetirizine (Zyrtec®), fexofenadine (Allegra®) and loratadine (Claritin®) – marketed as “nonsedating” – usually cause less drowsiness. An added benefit is that second-generation antihistamines last longer than Benadryl. Allegra is generally the least sedating.

Nasal spray antihistamines are also somewhat less likely to make you sleepy, since they target nasal passages directly rather than sending medicine throughout your body in the bloodstream. These are available only by prescription.

Regular use of an intranasal corticosteroid is not only safe but also an effective way to reduce use of antihistamines. They take a few days to start working, so you need to be patient. Ask your doctor or pharmacist about using an antihistamine with an intranasal corticosteroid the first few days. Some intranasal corticosteroids are available over-the-counter, while others are available as prescription medication.

To avoid daytime drowsiness, take an antihistamine in the evening rather than in the morning. It may help you sleep, with drowsy effects wearing off by the next morning. Be aware that drowsiness can last longer than you might expect – and that some antihistamines can cause vivid dreams.

Don’t drink alcohol when taking antihistamines, as it will increase the sedation.

What about antihistamines in cold and flu medications?

What many people may not know is that cold and flu medicines marketed to treat runny nose and sneezing usually include first-generation antihistamines – the more sedating types. That’s because they are often better at treating cold symptoms and drying up runny nose than the newer types.

Because of their sedating effect, cold medicines with antihistamines are labeled for nighttime use. Take this labeling seriously, as some include medications like doxylamine that are more sedating than others. Check labels for dosages as well, as these may vary, even within brands.

More is not better – read labels carefully and take only as recommended. Don’t supplement a multi-symptom cold medication with another single-ingredient antihistamine.

Be smart, be aware of allergy medication side effects

Smart use of allergy medications – knowing how they treat symptoms of an allergic reaction, being aware of potential unwanted side effects and, most important, monitoring their effect on you and your health – is just one step toward controlling allergy and cold symptoms. Even more important: knowing what you are allergic to and taking steps to prevent or reduce exposure.

If your allergy symptoms tend to last longer than two weeks or are not adequately controlled with over-the-counter medications, schedule an appointment with a board-certified allergist for a full diagnosis.

Antihistamines and intranasal corticosteroids are intended for symptom relief. If antihistamines or intranasal corticosteroids are causing side effects such as drowsiness or other problems, there are other treatment options your doctor can offer for relief from allergic reactions. These options include allergen immunotherapy and non-drowsy allergy medicines like second-generation antihistamines or nasal sprays.

Reviewed by:
Dennis Williams, PharmD, is an Associate Professor at the University of North Carolina Eshelman School of Pharmacy. He practices at UNC Medical Center with the pulmonary medicine medical service. He has served as a member of the National Asthma Education Program Coordinating Committee and the National Asthma Educator Certification Board. He serves on Allergy & Asthma Network’s Board of Directors.

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Product Information

• Adults and children 12 years of age and over:
• Take one 180 mg tablet with water once a day; do not take more than 1 tablet in 24 hours.
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• Adults 65 years of age and older: ask a doctor.
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Do not use if you have ever had an allergic reaction to this product or any of its ingredients.

Ask a doctor before use if you have kidney disease. Your doctor should determine if you need a different dose.

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If pregnant or breastfeeding, ask a health professional before use.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center right away.

For 30 count or larger count sizes:

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For 15 count or smaller count sizes:

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Ingredients

Active Ingredients

Fexofenadine HCl 180 mg (in each tablet)

An antihistamine that works to relieve allergy symptoms of sneezing, runny nose, itchy/watery eyes, and itchy nose or throat due to hay fever or other upper respiratory allergies.

Purpose: Antihistamine

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Get tips for managing indoor and outdoor allergies

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Allergy season is different for everyone. That’s because different kinds of outdoor allergens — or irritants — get distributed into the air year-round.

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What and how to treat allergies?

With various allergic symptoms – runny nose, conjunctivitis, urticaria, etc. – we, of course, resort to the help of antihistamines. But at the same time, we rarely think about their features: for example, to which generation this or that remedy belongs, what side effects it has. And it should.

Determining the diagnosis

Let’s start with what is currently known two generations of antihistamines . The first antihistamines began to be used in the 40-50s of the last century. These drugs initially had a number of serious side effects, which, however, did not prevent them from “gaining popularity” – the work on their creation was even awarded the Nobel Prize! ²
Meanwhile, medicine was advancing. In the 1980s, 2nd generation antihistamines appeared. They acted faster, more efficiently and were deprived of a number of side effects. But, nevertheless, many representatives of first-generation antihistamines continue to be widely used, and this despite the fact that reports of undesirable consequences of their use appeared almost 60 years ago! ¹
To this day, we continue to treat allergies with outdated remedies. Out of ignorance or “out of habit” – it doesn’t matter! Agree, if there are more modern and safe drugs, it is unreasonable to use their less successful predecessors, which can harm the health of you and your children.
Still in doubt? Let’s talk in more detail about the dangers of first-generation antihistamines, what advantages second-generation drugs have over them, and which of their representatives should be remembered.

Diagnosis established

“Search and neutralize” ²
Imagine: an allergen enters the body, an allergic reaction begins, during which histamine is released. By binding to receptors, this substance causes swelling, redness of the skin, bronchospasm, difficulty in nasal breathing, so it is very important to block its action, stop the inflammatory reaction.
Histamine receptors are found in blood vessels, smooth muscles, the heart, tissues of the central nervous system, epithelium, and also in the brain. ⁷ In order to relieve allergy symptoms, it is enough to act on peripheral receptors. However, first-generation antihistamines also block receptors in the brain, resulting in a number of side effects:
– They act on the central nervous system, and therefore cause sedation – drowsiness, inhibition of reactions .
– Their action is not stable and durable, which makes it necessary to use high doses several times a day (up to 4-6 times) of these drugs. ( And this despite the fact that the therapeutic concentration is reached only after 2 hours! ³ ) As a result, when using these drugs, there is a possibility of a whole range of side effects: drowsiness, dizziness, lethargy, impaired coordination, inability to concentrate.
– They do not have selectivity (“targeting” action on histamine receptors), they also block other types of receptors, which can cause tachycardia, dryness of the nasopharynx and oral cavity, urinary retention, constipation, and visual impairment. The condition of bronchial asthma may even be aggravated (sputum viscosity increases) and cardiac arrhythmia may occur as a result of toxic effects on the heart. ¹
– May be addictive, and with prolonged (more than 7-10 days) use, the therapeutic activity of the drug decreases.
It is clear that in diseases such as bronchial asthma, chronic urticaria and perennial allergic rhinitis, requiring long-term use of antihistamines, the use of first-generation drugs is highly undesirable. ²
Mistakes we make ¹
Perhaps the biggest mistake of using 1st generation drugs is that many mothers give these drugs to babies before bed at night, hoping that the sedative effect will contribute to a deeper sleep of the child.
In the course of recent studies of the effect of 1st generation antihistamines on the functioning of the brain, it was proved that they cause unnatural sleep, disrupt the course of sleep phases! ¹ The onset of REM sleep (necessary for memory formation and brain development) is delayed, its duration is reduced. The use of first-generation antihistamines often leads to daytime sleepiness, reduced daytime activity, and impaired brain function, which is especially dangerous when they are used in children.

It has also been proven that 1st generation drugs contribute to a significant decrease in the ability of schoolchildren to learn, impaired concentration and memory.
With the regular use of such funds, cognitive functions (the ability of the brain to perceive and process information) are seriously affected, and therefore there is a threat to the full intellectual development of the child.

A special study was conducted in the UK with 1,834 teenage students taking exams. Among the students were those who suffered from allergic rhinitis. They were divided into two groups – those who were not treated with anything, and those who took first-generation antihistamines. For the former, the probability of “failing” the exam was 40%, for the latter – 70%. ¹
In general, it becomes clear why many developed countries are raising the issue of limiting the use of first-generation antihistamines without a prescription. ²
So, if you see one of the following substances on the package or in the instructions, know that you have a 1st generation antihistamine in your hands: Diphenhydramine, chloropyramine, promethazine, dimethindene, clemastine, mebhydrolin, etc. . ²

New generation chooses… ^2.3
What kind of allergy medications do we, modern people, need? Well, of course, those that:
– act quickly and efficiently;
– in therapeutic doses, they practically do not have a sedative effect;
– work even at a high concentration of histamine in the blood, without harming the body;
– suitable for the treatment of most allergic diseases, including chronic forms;
– practically do not affect the ability of children to learn and concentrate;
– contribute to improving the quality of life against the background of the current allergic disease.
It is these qualities that second-generation antihistamines have. These drugs include cetirizine (Zodak®), levocetirizine (Zodak Express®), and fexofenadine (Allegra).
These drugs can also be taken by children. Zodak® in the form of drops can be used in children from 6 months. ⁴ A Zodak® and Zodak Express® tablets are approved for use from 6 years of age.