A nurse is teaching a client who has a new prescription for an antacid to treat a gastric ulcer. Which of the following statements by the client indicates an understanding of the teaching?

Choice A reason: Bradycardia is not an adverse effect of diphenhydramine. Diphenhydramine is a medication that blocks the action of histamine, a chemical that causes allergic reactions and inflammation. Diphenhydramine can also block the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Diphenhydramine does not affect the heart rate or blood pressure significantly, and it is not associated with bradycardia, which is a slow heart rate that can cause dizziness, fatigue, or fainting. The nurse should monitor the vital signs of the client after administering diphenhydramine, but bradycardia is not a common or expected outcome.

Choice B reason: Sedation is an adverse effect of diphenhydramine. Diphenhydramine is a medication that blocks the action of histamine, a chemical that causes allergic reactions and inflammation. Diphenhydramine can also block the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Diphenhydramine can cross the bloodbrain barrier and block the histamine receptors in the brain, which are involved in regulating the sleepwake cycle and alertness. Diphenhydramine can cause sedation, sleepiness, drowsiness, dizziness, and impaired coordination, which can affect the performance and safety of the client. The nurse should instruct the client to avoid driving, operating machinery, or performing other tasks that require mental alertness after taking diphenhydramine, and to take the medication at bedtime or as needed for sleep.

Choice C reason: Constipation is not an adverse effect of diphenhydramine. Diphenhydramine is a medication that blocks the action of histamine, a chemical that causes allergic reactions and inflammation. Diphenhydramine can also block the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Diphenhydramine does not affect the gastrointestinal motility or secretion significantly, and it is not associated with constipation, which is a condition of infrequent or difficult bowel movements. The nurse should encourage the client to eat a balanced and highfiber diet, drink plenty of fluids, and exercise regularly to prevent or treat constipation, but diphenhydramine is not a contributing factor.

Choice D reason: Hypertension is not an adverse effect of diphenhydramine. Diphenhydramine is a medication that blocks the action of histamine, a chemical that causes allergic reactions and inflammation. Diphenhydramine can also block the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Diphenhydramine does not affect the blood pressure or the vascular tone significantly, and it is not associated with hypertension, which is a condition of high blood pressure that can cause headaches, chest pain, or stroke. The nurse should monitor the blood pressure of the client after administering diphenhydramine, but hypertension is not a common or expected outcome.

Choice A reason: This is incorrect. Miosis is the constriction of the pupils, which can also be caused by morphine, but it is not a life-threatening side effect. Miosis occurs because morphine stimulates the parasympathetic nervous system, which controls the muscles that constrict the pupils¹.

Choice B reason: This is incorrect. Sedation is the state of being calm, relaxed, and sleepy, which can also be caused by morphine, but it is not a life-threatening side effect. Sedation occurs because morphine depresses the central nervous system, which reduces the activity of the brain and the body.

Choice C reason: This is correct. Respiratory depression is the slowing down of breathing, which can be a life-threatening side effect of morphine. Respiratory depression occurs because morphine depresses the respiratory center in the brainstem, which regulates the rate and depth of breathing. If the breathing becomes too slow or shallow, the patient may not get enough oxygen and may lose consciousness or die.

Choice D reason: This is incorrect. Euphoria is the feeling of intense happiness, pleasure, or wellbeing, which can also be caused by morphine, but it is not a life-threatening side effect. Euphoria occurs because morphine stimulates the reward system in the brain, which releases dopamine, a neurotransmitter that causes positive emotions.