shift is wild

Pharmacology · chapter 24 · Upper Respiratory Disorder Drugs

Antihistamines and Decongestants

The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.

Skip to the questions ↓

Key points

  1. Why first-generation drugs cause drowsiness

    These medications impact the histamine receptors present in the brain and spinal cord. Because they can penetrate the blood–brain barrier, they may lead to drowsiness as a side effect.

  2. First-generation adverse effects

    First-generation antihistamines can cause drowsiness, dizziness, confusion, and urinary retention. Clients with a history of urinary retention or prostatic hyperplasia should use first-generation antihistamines cautiously.

  3. Avoid first generation in older adults

    First-generation antihistamines should be avoided in older clients. Their highly anticholinergic properties can increase the risk of dementia, and clearance of the drug is reduced in clients of advanced age.

  4. Second generation causes less drowsiness

    This distinction leads to a significantly reduced occurrence of first-generation side effects, especially drowsiness, in second-generation antihistamines (Naqvi Gerriets, 2023).

  5. Fexofenadine in pregnancy and breastfeeding

    Clients who are pregnant or breastfeeding should seek advice from their health care provider before taking this medication because it can decrease breast milk production. It is not usually prescribed during pregnancy.

  6. Antihistamine overdose

    Ingesting antihistamines in doses exceeding the recommended amount, particularly diphenhydramine, may result in severe heart complications, seizures, unconsciousness, or even fatality. Clients should avoid combining antihistamines with substances that are also sedating (sedatives, alcohol, etc.)

  7. No driving on antihistamines

    Antihistamines can cause marked drowsiness and should be avoided when driving or operating machinery. Alcohol and other CNS depressants can increase drowsiness and should be avoided when taking antihistamines.

  8. Three-day limit for nasal sprays

    Nasal decongestants should be used for 3 days or less, as rebound congestion can occur. Rebound congestion is worsened congestion after the medication wears off.

  9. Oxymetazoline has no systemic effects

    Oxymetazoline is considered a local decongestant because it acts on the nasal tissue by narrowing the blood vessels and opening the air passages to allow for ease of breathing, producing no systemic effects. The lack of systemic effects can be beneficial to clients with hypertension or other cardiac disorders.

  10. Systemic decongestants raise blood pressure

    Systemic decongestants act on alpha-adrenergic receptors in the blood vessel walls and can cause an increase in blood pressure and affect the cardiovascular system. Clients with cardiac issues should use systemic decongestants with caution because they can also increase blood pressure.

  11. Pseudoephedrine teaching

    Clients should avoid caffeine when taking this drug, and those with blood pressure issues should discuss use of this medication with their health care provider.

  12. Phenylephrine for high blood pressure

    For clients with high blood pressure, phenylephrine should be used instead of pseudoephedrine. Phenylephrine has less impact on blood pressure than pseudoephedrine.

  13. Decongestants and young children

    Decongestants are not safe for children under age 6. Clients should increase fluid intake when taking any cold medication, including decongestants.

  14. Fall precautions for older clients

    Initiate fall precautions for older clients due to the adverse effects of hypotension, dizziness, and drowsiness (antihistamines).

Terms to know

Rebound congestion
Rebound congestion is worsened congestion after the medication wears off.
Histamines
Histamines are released by the body as part of the immune response to a foreign substance such as an allergen or pathogen.
Decongestant
Decongestant s refer to medications that offer temporary relief for a blocked nose or nasal congestion.

Practice questions

Stuck on select-all-that-apply? How to take them one option at a time.

The graded version needs JavaScript. Every question is below anyway, with the answer and why.

Every question here, with the answer

  1. An 82-year-old client asks for diphenhydramine to help with sleep. What is the nurse's best response?

    1. Explain that first-generation antihistamines should be avoided in older clients and consult the provider.
    2. Give it with a glass of wine to improve sleep.
    3. Give a double dose because clearance is faster in older adults.
    4. Give it; it is the safest sleep aid for older adults.

    Answer: Explain that first-generation antihistamines should be avoided in older clients and consult the provider.

    First-generation antihistamines should be avoided in older clients because their anticholinergic properties increase dementia risk and clearance is reduced. Doubling the dose or adding alcohol increases sedation and harm.

  2. A client has used oxymetazoline nasal spray for a week and says the congestion is now worse than before. What does the nurse suspect?

    1. An allergy to the spray
    2. A sinus infection that needs antibiotics
    3. The spray was not used often enough
    4. Rebound congestion from use longer than 3 days

    Answer: Rebound congestion from use longer than 3 days

    Nasal decongestants should be used for 3 days or less; overuse leads to rebound congestion, which is worsened congestion after the medication wears off. Using it more often would make it worse.

  3. A client with hypertension needs an oral decongestant for a cold. Which choice is safer?

    1. Phenylephrine
    2. Pseudoephedrine taken with coffee
    3. Any decongestant at double dose
    4. Pseudoephedrine

    Answer: Phenylephrine

    For clients with high blood pressure, phenylephrine should be used instead of pseudoephedrine because it has less impact on blood pressure. Caffeine should be avoided with pseudoephedrine, and exceeding doses is unsafe.

  4. A nurse is teaching a client who is taking a first-generation antihistamine. Which instructions should be included? Select all that apply.

    1. Use sugarless candies or lozenges for dry mouth.
    2. Take an extra dose if symptoms continue.
    3. Avoid alcohol.
    4. Do not take more than one antihistamine at a time.
    5. Do not drive or operate machinery.

    Answer: Use sugarless candies or lozenges for dry mouth., Avoid alcohol., Do not take more than one antihistamine at a time., Do not drive or operate machinery.

    First-generation antihistamines cause drowsiness, alcohol adds to it, dry mouth is eased with sugarless candies or lozenges, and many OTC products already contain antihistamines. Exceeding the recommended amount can cause severe complications.

  5. A client is starting pseudoephedrine. Which teaching points are correct? Select all that apply.

    1. Take any other OTC cold product with it freely.
    2. Do not take it within 2 hours of bedtime.
    3. Drink fluids and stay hydrated.
    4. Avoid caffeine and alcohol.
    5. It is safe for children under age 6.

    Answer: Do not take it within 2 hours of bedtime., Drink fluids and stay hydrated., Avoid caffeine and alcohol.

    Clients taking a decongestant avoid caffeine and alcohol, avoid taking it within 2 hours of bedtime because of insomnia, and maintain hydration. Other OTC drugs require consulting the provider, and decongestants are not safe for children under 6.

  6. A 70-year-old man with prostatic hyperplasia takes diphenhydramine. Which assessment is most important?

    1. Bowel sounds
    2. Blood glucose
    3. Hearing
    4. Urinary output for retention

    Answer: Urinary output for retention

    First-generation antihistamines can cause urinary retention and should be used cautiously in prostatic hyperplasia, so the nurse monitors urinary input and output. The other assessments are not linked to this adverse effect.

Where every quote comes from

Section 24.1 Antihistamines and Decongestants of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.

The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.