24.1 Antihistamines and Decongestants
2 min read•june 18, 2024
and are key players in managing allergies and congestion. These meds work by blocking or shrinking swollen nasal passages, offering relief from sneezing, itching, and stuffiness.
When using these drugs, it's crucial to know the differences between first and and oral versus topical decongestants. Side effects and interactions vary, so proper use and monitoring are essential for safe, effective symptom management.
Antihistamines and Decongestants
Key characteristics and mechanisms of action
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- Antihistamines block histamine receptors (H1) in the body reducing histamine-mediated symptoms (sneezing, itching, runny nose)
- (, ) cross the blood-brain barrier causing
- (, ) less likely to cross blood-brain barrier with less sedation
- Decongestants stimulate in causing and reducing
- Oral decongestants (, ) systemically absorbed potentially causing increased blood pressure and heart rate
- Topical decongestants (, xylometazoline) act locally in nasal passages with fewer systemic side effects
Indications, side effects, and drug interactions
- Indications include , hay fever, other upper respiratory allergies, and common cold symptoms (sneezing, runny nose, nasal congestion)
- Antihistamine side effects: sedation (more common with first-generation), dry mouth/eyes/nose, constipation, blurred vision
- side effects: increased blood pressure/heart rate, , anxiety, restlessness, with prolonged topical use
- Antihistamine interactions: alcohol and CNS depressants increase sedation, anticholinergics increase dry mouth and constipation
- Decongestant interactions: MAOIs can cause severe , stimulants (amphetamines) increase cardiovascular side effects
Critical nursing considerations
- Assessment: evaluate symptoms and history, check for allergies/contraindications, monitor vitals (blood pressure, heart rate with decongestants)
- Administration: follow prescribed dosage and route, educate on proper use (topical decongestants), advise avoiding alcohol/CNS depressants with antihistamines
- Monitoring: assess medication effectiveness in relieving symptoms, monitor for side effects/adverse reactions, encourage reporting unusual symptoms or concerns
Patient education plan
- Proper use
- Follow prescribed dosage and frequency
- Use topical decongestants for no more than 3-5 consecutive days avoiding
- Do not exceed recommended daily dose of oral decongestants
- Precautions: avoid alcohol/CNS depressants with antihistamines, use caution driving or operating machinery (especially ), consult healthcare provider before using decongestants with hypertension, heart disease, or diabetes
- Non-pharmacological measures: minimize allergen exposure (dust, pollen), recommend nasal saline irrigation for congestion relief, advise staying hydrated and getting adequate rest
- Follow-up: schedule appointments to assess treatment plan effectiveness, encourage contacting healthcare provider if symptoms worsen or persist despite treatment
Key Terms to Review (67)
Acute angle-closure (narrow-angle) glaucoma: Acute angle-closure (narrow-angle) glaucoma is a type of glaucoma where the iris blocks the drainage angle in the eye, leading to a rapid increase in intraocular pressure. This condition is an ocular emergency requiring immediate treatment to prevent vision loss.
Afrin: Afrin is a decongestant medication that works by constricting blood vessels in the nasal passages, reducing inflammation and relieving nasal congestion. It is commonly used to treat symptoms associated with colds, allergies, and sinus infections.
Allegra: Allegra, also known by its generic name fexofenadine, is a second-generation antihistamine used to treat symptoms of allergic rhinitis and chronic idiopathic urticaria (hives). It works by blocking the action of histamine, a substance in the body that causes allergic symptoms.
Allergic Response: An allergic response is an overreaction of the immune system to a normally harmless substance, triggering the release of chemicals like histamine that cause inflammation and other symptoms. This term is particularly relevant in the context of understanding antihistamines and decongestants, which are medications used to manage and alleviate the symptoms of allergic reactions.
Allergic Rhinitis: Allergic rhinitis is a condition characterized by an inflammation of the nasal passages, typically caused by an allergic response to environmental triggers such as pollen, dust, or pet dander. It is a common upper respiratory condition that can significantly impact a person's quality of life.
Alpha-Adrenergic Receptors: Alpha-adrenergic receptors are a class of G-protein coupled receptors that bind to the neurotransmitter norepinephrine and mediate various physiological responses in the body. These receptors play a crucial role in regulating cardiovascular function, blood pressure, and other autonomic processes.
Anticholinergic Effects: Anticholinergic effects refer to the disruption or blockade of the neurotransmitter acetylcholine, which is responsible for various physiological functions. These effects can be seen with the use of certain medications, particularly antidepressants and antihistamines.
Antihistamines: Antihistamines are medications that block histamine receptors to reduce allergy symptoms such as itching, swelling, and rashes. They are commonly used to treat allergic reactions, upper respiratory disorders, and sometimes in combination with other drugs for various conditions.
Benadryl: Benadryl is a brand name for diphenhydramine, an antihistamine commonly used to treat allergic reactions and symptoms of the common cold. It works by blocking histamine receptors in the body, reducing allergy symptoms such as itching, sneezing, and runny nose.
Benign Prostatic Hyperplasia: Benign prostatic hyperplasia (BPH) is a noncancerous enlargement of the prostate gland, a common condition in older men that can lead to urinary symptoms. This term is relevant in the context of understanding drugs that treat nervous system disorders, antihistamines and decongestants, phosphodiesterase 5 inhibitors, the male reproductive system, and alpha blockers and 5-alpha-reductase inhibitors.
Benign prostatic hyperplasia (BPH): Benign prostatic hyperplasia (BPH) is a non-cancerous enlargement of the prostate gland that commonly affects older men. It can lead to urinary symptoms such as difficulty starting urination and weak urine flow.
Brompheniramine: Brompheniramine is an antihistamine used to relieve symptoms of allergy, hay fever, and the common cold. It works by blocking histamine, a substance in the body that causes allergic symptoms.
Cetirizine: Cetirizine is an antihistamine used to relieve allergy symptoms such as watery eyes, runny nose, itching eyes/nose, and sneezing. It works by blocking histamine, a substance in the body that causes allergic symptoms.
Cetirizine: Cetirizine is a second-generation antihistamine medication primarily used to treat symptoms of allergic rhinitis, such as sneezing, itching, and watery eyes. It works by blocking the action of histamine, a chemical released by the body during an allergic reaction, to provide relief from allergy symptoms.
Children: Children are individuals in the developmental stage between infancy and adolescence. Their physiological and psychological characteristics impact how they respond to various pharmacological treatments.
Chlor-Trimeton: Chlor-Trimeton is a brand name for chlorpheniramine, an antihistamine used to relieve symptoms of allergy, hay fever, and the common cold. It works by blocking histamine, a substance in the body that causes allergic symptoms.
Chlorpheniramine: Chlorpheniramine is an antihistamine used to relieve allergy symptoms such as runny nose, sneezing, and itching. It works by blocking the action of histamine in the body.
Clarinex: Clarinex is a brand name for desloratadine, a non-drowsy antihistamine used to relieve allergy symptoms such as runny nose and itchy eyes. It works by blocking histamine, a substance in the body that causes allergic symptoms.
Claritin: Claritin is an over-the-counter antihistamine used to relieve allergy symptoms such as runny nose, sneezing, and itchy eyes. It contains loratadine, a second-generation antihistamine that does not usually cause drowsiness.
Decongestant: A decongestant is a medication used to relieve nasal congestion in the upper respiratory tract. It works by narrowing the blood vessels in the nasal passages, reducing swelling and congestion.
Decongestants: Decongestants are a class of medications that work by reducing nasal and sinus congestion by constricting blood vessels and decreasing swelling in the nasal passages. They are commonly used to relieve symptoms associated with colds, allergies, and other upper respiratory conditions.
Desloratadine: Desloratadine is a second-generation antihistamine used to relieve allergy symptoms. It works by blocking histamine receptors without causing significant drowsiness.
Dimetapp: Dimetapp is an over-the-counter medication commonly used to relieve symptoms of upper respiratory disorders such as nasal congestion and allergies. It typically contains a combination of an antihistamine and a decongestant.
Diphenhydramine: Diphenhydramine is an antihistamine commonly used to relieve symptoms of allergy, hay fever, and the common cold. It also has sedative properties and is sometimes used as a sleep aid.
Drug Interactions: Drug interactions occur when the effects of one drug are altered by the presence of another drug, food, or other substance in the body. These interactions can lead to changes in the drug's intended therapeutic effects, side effects, or both, potentially impacting the overall safety and efficacy of the medication regimen.
Fexofenadine: Fexofenadine is a second-generation antihistamine used to treat allergy symptoms such as hay fever and urticaria. It works by blocking histamine H1 receptors, reducing allergic reactions.
First-generation antihistamines: First-generation antihistamines are medications that block histamine H1 receptors to alleviate allergic symptoms. They often cause sedation due to their ability to cross the blood-brain barrier.
First-Generation Antihistamines: First-generation antihistamines are a class of drugs that block the action of histamine, a chemical released by the body during allergic reactions. They are considered the older or traditional type of antihistamines, known for their sedative effects and potential for causing drowsiness.
Glaucoma: Glaucoma is a group of eye conditions that can damage the optic nerve, often due to increased pressure within the eye. It is a leading cause of irreversible blindness worldwide and can affect various aspects of the nervous system, eyes, and fluid regulation in the body.
Grades of hypertension: Grades of hypertension classify the severity of high blood pressure based on systolic and diastolic measurements. These grades help guide treatment decisions and risk assessment.
H1 receptors: H1 receptors are a type of histamine receptor found in various tissues, including the upper respiratory tract. They play a key role in mediating allergic reactions and inflammation.
H1 Receptors: H1 receptors are a type of histamine receptor found in various tissues throughout the body. They are the primary targets of antihistamine drugs and play a crucial role in mediating the physiological effects of histamine, particularly in the context of allergic reactions and inflammation.
Histamine: Histamine is a chemical compound that is naturally produced in the body and plays a crucial role in the inflammatory response, as well as in the regulation of various physiological processes. It is an important mediator in the body's immune system and is involved in the pathogenesis of various allergic and inflammatory conditions.
Hypertension: Hypertension, also known as high blood pressure, is a chronic medical condition in which the blood pressure in the arteries is elevated, increasing the risk of heart disease, stroke, and other health complications. It is a key term that is closely connected to various topics in pharmacology, including the management of cardiovascular conditions and the use of specific drug classes to control blood pressure.
Immune system: The immune system is a complex network of cells, tissues, and organs that work together to defend the body against harmful pathogens like bacteria, viruses, and fungi. It plays a crucial role in maintaining health by identifying and neutralizing foreign invaders.
Insomnia: Insomnia is a sleep disorder characterized by difficulty falling asleep, staying asleep, or waking up too early and not being able to go back to sleep. It can have a significant impact on an individual's overall health and quality of life.
Levocetirizine: Levocetirizine is a third-generation antihistamine used to treat symptoms of allergic rhinitis and chronic urticaria. It works by blocking histamine receptors to reduce allergy symptoms.
Loratadine: Loratadine is a second-generation antihistamine used to relieve symptoms of allergy such as runny nose, sneezing, and itching. It has fewer sedative effects compared to first-generation antihistamines.
Mast Cells: Mast cells are immune cells that play a crucial role in the body's inflammatory and allergic responses. They are found in various tissues, particularly those exposed to the external environment, and are known for their ability to release a variety of potent chemical mediators upon activation.
Methamphetamine: Methamphetamine is a powerful central nervous system stimulant primarily used to treat ADHD and certain cases of obesity. It has a high potential for abuse and addiction.
Monoamine oxidase inhibitors (MAOIs): Monoamine oxidase inhibitors (MAOIs) are a class of antidepressant medications that work by inhibiting the activity of monoamine oxidase enzymes. This increases the levels of neurotransmitters such as serotonin, norepinephrine, and dopamine in the brain.
Motion Sickness: Motion sickness is a physiological condition that occurs when there is a disconnect between the visual and vestibular systems, leading to symptoms like nausea, vomiting, and dizziness. This term is particularly relevant in the context of antihistamines, decongestants, and antiemetics, as these drug classes can be used to prevent or treat the symptoms of motion sickness.
Muscarinic: Muscarinic receptors are a type of acetylcholine receptor that are G protein-coupled and found in various tissues such as the heart, smooth muscles, and glands. They play a crucial role in mediating parasympathetic nervous system responses.
Nasal Congestion: Nasal congestion, also known as a stuffy nose, is a common condition characterized by the blockage or obstruction of the nasal passages, making it difficult to breathe through the nose. It is often associated with inflammation or swelling of the nasal tissues and can be caused by a variety of factors, including allergies, infections, and environmental irritants.
Nasal decongestants: Nasal decongestants are medications used to alleviate nasal congestion by reducing the swelling of the nasal passages. They work either by constricting blood vessels in the nasal tissues or by thinning mucus.
Nasal Mucosa: The nasal mucosa is the moist, thin lining of the nasal cavity that plays a crucial role in the body's respiratory and immune functions. It is an important structure within the context of antihistamines and decongestants, as it is the primary site of action for these medications.
Older clients: Older clients are patients typically aged 65 and above who may have unique health considerations due to age-related physiological changes. These changes often necessitate specialized pharmacological approaches.
Oxymetazoline: Oxymetazoline is a sympathomimetic amine that acts as a selective alpha-adrenergic receptor agonist. It is primarily used as a decongestant to relieve nasal and sinus congestion by constricting blood vessels and reducing swelling in the nasal passages.
Phenylephrine: Phenylephrine is a selective alpha-1 adrenergic receptor agonist used as a decongestant. It works by constricting blood vessels in the nasal passages, reducing swelling and congestion.
Pseudoephedrine: Pseudoephedrine is an oral decongestant commonly used to relieve nasal congestion caused by colds, allergies, or hay fever. It works by shrinking the blood vessels in the nasal passages.
Rebound congestion: Rebound congestion is the worsening of nasal congestion due to the overuse of topical nasal decongestants. It occurs when the medication is used for more than three to five consecutive days, causing the nasal passages to become inflamed and congested once the medication wears off.
Rebound Congestion: Rebound congestion refers to the temporary worsening of nasal congestion that can occur after the use of decongestant medications is discontinued. This phenomenon is a result of the body's physiological response to the sudden withdrawal of the decongestant's effects.
Second-generation antihistamines: Second-generation antihistamines are medications used to treat allergic reactions and symptoms of upper respiratory disorders. They are preferred over first-generation antihistamines due to fewer sedative effects.
Second-Generation Antihistamines: Second-generation antihistamines are a class of medications that work to block the effects of histamine, a chemical released by the body during an allergic reaction. Unlike first-generation antihistamines, these newer drugs have fewer side effects and are less likely to cause drowsiness or impair cognitive function.
Sedation: Sedation is the act of inducing a calming and relaxing effect on the body, often through the use of sedative medications. It is a key concept in the context of both opioid agonists/antagonists and antihistamines/decongestants, as these drug classes can have sedative properties that impact a patient's level of consciousness and arousal.
Sudafed: Sudafed is a brand name for pseudoephedrine, a decongestant used to relieve nasal congestion caused by colds, allergies, and sinus infections. It works by shrinking the blood vessels in the nasal passages.
Sudafed PE: Sudafed PE is an over-the-counter decongestant containing phenylephrine, used to relieve nasal congestion caused by colds, allergies, or hay fever. It works by narrowing the blood vessels in the nasal passages.
Sympathetic Nervous System: The sympathetic nervous system is a division of the autonomic nervous system that is responsible for the body's fight-or-flight response. It prepares the body to respond to perceived threats or stressful situations by increasing heart rate, blood pressure, and breathing rate, while also diverting blood flow away from the digestive system and towards the muscles.
Systemic decongestants: Systemic decongestants are medications taken orally to relieve nasal congestion by constricting blood vessels in the nasal passages. They reduce swelling and improve airflow, often used for colds and allergies.
Tachycardia: Tachycardia refers to a rapid heart rate, typically defined as a resting heart rate exceeding 100 beats per minute. This abnormally fast heart rhythm can have various underlying causes and is an important consideration in several medical conditions and drug therapies.
Third-generation antihistamines: Third-generation antihistamines are advanced medications derived from second-generation antihistamines, designed to treat allergic reactions with minimal sedation and fewer side effects. They provide long-lasting relief by selectively inhibiting histamine H1 receptors.
Urinary Retention: Urinary retention is the inability to completely empty the bladder, resulting in a buildup of urine within the bladder. This condition can have various underlying causes and is an important consideration across several medication classes.
Urticaria: Urticaria, commonly known as hives, is a skin reaction characterized by itchy welts that can vary in size and appear anywhere on the body. It is often triggered by an allergic reaction or exposure to certain drugs.
Urticaria: Urticaria, also known as hives, is a skin condition characterized by the sudden appearance of red, itchy, and swollen welts or bumps on the skin. It is a common allergic reaction that can be triggered by various factors and is closely related to the use of antihistamines and decongestants in the management of this condition.
Vasoconstriction: Vasoconstriction is the narrowing or constriction of blood vessels, specifically the arteries and arterioles, which leads to a decrease in blood flow and blood pressure. This physiological process is an important mechanism in the regulation of blood flow and blood pressure throughout the body.
Xyzal: Xyzal is a brand name for levocetirizine, an antihistamine used to relieve symptoms of allergic rhinitis and chronic idiopathic urticaria. It works by blocking histamine receptors and reducing the effects of natural histamine in the body.
Zyrtec: Zyrtec is a brand name for cetirizine, an antihistamine used to relieve allergy symptoms such as runny nose, sneezing, and itching. It is commonly used to treat both seasonal allergies and chronic urticaria (hives).