NUR 635 CHAPTER 56 ANTIHISTAMINES STUDY GUIDE 2026/2027 | PRACTICE QUESTIONS,
VERIFIED ANSWERS & COMPREHENSIVE PHARMACOLOGY REVIEW
555. A provider has ordered intravenous promethazine [Phenergan] for an adult patient
postoperatively to prevent nausea and vomiting (N/V). What will the nurse do?
a. Administer the drug at a rate of 25 mg/minute or more to achieve maximum effects.
b. Contact the provider to suggest using dimenhydrinate [Dramamine] instead.
c. Ensure that the IV is infusing freely through a large-bore needle.
d. Monitor the patient closely for cardiac dysrhythmias. - correct answer ✔✔ANS: C
Promethazine can cause severe local tissue injury if it extravasates into tissues, so the
medication should be administered in an IV that is flowing freely through a large-bore needle.
The drug should be administered at a rate of 25 mg/minute or less. Dimenhydrinate is indicated
for motion sickness, not postoperative N/V. Cardiac dysrhythmias were a concern with two
antihistamines no longer on the market, astemizole and terfenadine.
556. A 5-year-old child is brought to the emergency department after ingesting
diphenhydramine [Benadryl]. The child is uncoordinated and agitated. The nurse observes that
the child's face is flushed, the temperature is 37.1°C, and the heart rate is 110 beats/minute.
The nurse will expect to:
a. administer atropine to reverse the adverse effects.
b. apply ice packs to stop the flushing.
c. give activated charcoal to absorb the drug.
d. prepare to provide mechanical ventilation. - correct answer ✔✔ANS: C
In acute toxicity, patients present with agitation, a flushed face, tachycardia, and uncoordinated
movements. There is no specific antidote, so drug removal is the focus of treatment, starting
with activated charcoal to absorb the drug, followed by a cathartic to enhance excretion.
Atropine would cause an increase in the heart rate. Application of ice packs is recommended for
hyperthermia and not for flushing. The child's temperature is normal. Mechanical ventilation is
not indicated with this presentation of symptoms, although cardiovascular collapse may
eventually develop.
, 557. A 5-year-old child with seasonal allergies has been taking 2.5 mL of cetirizine [Zyrtec] syrup
once daily. The parents tell the nurse that the child does not like the syrup, and they do not
think that the drug is effective. The nurse will suggest they discuss which drug with their child's
health care provider?
a. Cetirizine [Zyrtec] 5-mg chewable tablet once daily
b. Loratadine [Claritin] 10-mg chewable tablet once daily
c. Fexofenadine [Allegra] syrup 5 mL twice daily
d. Desloratadine [Clarinex] 5-mg rapid-disintegrating tablet once daily - correct answer ✔✔ANS:
A
The child is receiving a low dose of cetirizine and can receive up to 5 mg/day in either a single
dose or two divided doses. Cetirizine is available in a chewable tablet, which this child may
tolerate better, so the parents should be encouraged to explore this option with their provider.
The loratadine 10-mg chewable tablet is approved for children 6 years and older. Fexofenadine
would be safe for this child, but it is unlikely that the syrup would be any better than the
cetirizine syrup. Desloratadine is not approved for children under the age of 12 years.
558. A patient will begin taking fexofenadine [Allegra] for hay fever. The nurse teaching this
patient will tell the patient that:
a. fexofenadine should be taken with food to prevent gastrointestinal (GI) symptoms.
b. the medication may be taken once or twice daily.
c. tolerance to sedation will occur in a few weeks.
d. with renal impairment, this drug should be taken every other day. - correct answer ✔✔ANS:
B
Fexofenadine may be given 60 mg twice daily or 180 mg once daily. Fexofenadine does not need
to be given with food. Sedation is not a common side effect of fexofenadine. There is no caution
to reduce the dosage or increase the dosing interval in patients with renal impairment who take
fexofenadine.
559. A pregnant patient asks the nurse if she can take antihistamines for seasonal allergies
during her pregnancy. What will the nurse tell the patient?
a. Antihistamines should be avoided unless absolutely necessary.
VERIFIED ANSWERS & COMPREHENSIVE PHARMACOLOGY REVIEW
555. A provider has ordered intravenous promethazine [Phenergan] for an adult patient
postoperatively to prevent nausea and vomiting (N/V). What will the nurse do?
a. Administer the drug at a rate of 25 mg/minute or more to achieve maximum effects.
b. Contact the provider to suggest using dimenhydrinate [Dramamine] instead.
c. Ensure that the IV is infusing freely through a large-bore needle.
d. Monitor the patient closely for cardiac dysrhythmias. - correct answer ✔✔ANS: C
Promethazine can cause severe local tissue injury if it extravasates into tissues, so the
medication should be administered in an IV that is flowing freely through a large-bore needle.
The drug should be administered at a rate of 25 mg/minute or less. Dimenhydrinate is indicated
for motion sickness, not postoperative N/V. Cardiac dysrhythmias were a concern with two
antihistamines no longer on the market, astemizole and terfenadine.
556. A 5-year-old child is brought to the emergency department after ingesting
diphenhydramine [Benadryl]. The child is uncoordinated and agitated. The nurse observes that
the child's face is flushed, the temperature is 37.1°C, and the heart rate is 110 beats/minute.
The nurse will expect to:
a. administer atropine to reverse the adverse effects.
b. apply ice packs to stop the flushing.
c. give activated charcoal to absorb the drug.
d. prepare to provide mechanical ventilation. - correct answer ✔✔ANS: C
In acute toxicity, patients present with agitation, a flushed face, tachycardia, and uncoordinated
movements. There is no specific antidote, so drug removal is the focus of treatment, starting
with activated charcoal to absorb the drug, followed by a cathartic to enhance excretion.
Atropine would cause an increase in the heart rate. Application of ice packs is recommended for
hyperthermia and not for flushing. The child's temperature is normal. Mechanical ventilation is
not indicated with this presentation of symptoms, although cardiovascular collapse may
eventually develop.
, 557. A 5-year-old child with seasonal allergies has been taking 2.5 mL of cetirizine [Zyrtec] syrup
once daily. The parents tell the nurse that the child does not like the syrup, and they do not
think that the drug is effective. The nurse will suggest they discuss which drug with their child's
health care provider?
a. Cetirizine [Zyrtec] 5-mg chewable tablet once daily
b. Loratadine [Claritin] 10-mg chewable tablet once daily
c. Fexofenadine [Allegra] syrup 5 mL twice daily
d. Desloratadine [Clarinex] 5-mg rapid-disintegrating tablet once daily - correct answer ✔✔ANS:
A
The child is receiving a low dose of cetirizine and can receive up to 5 mg/day in either a single
dose or two divided doses. Cetirizine is available in a chewable tablet, which this child may
tolerate better, so the parents should be encouraged to explore this option with their provider.
The loratadine 10-mg chewable tablet is approved for children 6 years and older. Fexofenadine
would be safe for this child, but it is unlikely that the syrup would be any better than the
cetirizine syrup. Desloratadine is not approved for children under the age of 12 years.
558. A patient will begin taking fexofenadine [Allegra] for hay fever. The nurse teaching this
patient will tell the patient that:
a. fexofenadine should be taken with food to prevent gastrointestinal (GI) symptoms.
b. the medication may be taken once or twice daily.
c. tolerance to sedation will occur in a few weeks.
d. with renal impairment, this drug should be taken every other day. - correct answer ✔✔ANS:
B
Fexofenadine may be given 60 mg twice daily or 180 mg once daily. Fexofenadine does not need
to be given with food. Sedation is not a common side effect of fexofenadine. There is no caution
to reduce the dosage or increase the dosing interval in patients with renal impairment who take
fexofenadine.
559. A pregnant patient asks the nurse if she can take antihistamines for seasonal allergies
during her pregnancy. What will the nurse tell the patient?
a. Antihistamines should be avoided unless absolutely necessary.
