A nurse caring for a client receiving doxycycline (Doryx) for the treatment of Lyme's Disease. Which statement below should be included in the client teaching plan?

A. Avoid grapefruit juice while taking this medication:
Grapefruit juice is not a known interaction with doxycycline. While grapefruit juice can affect the metabolism of certain medications by inhibiting the cytochrome P450 enzymes (especially CYP3A4), doxycycline is not significantly metabolized through this pathway. Therefore, there is no specific recommendation to avoid grapefruit juice while taking doxycycline.

B. Take this medication with antacids to relieve gastrointestinal symptoms:
Taking doxycycline with antacids is not recommended, as antacids containing calcium, magnesium, or aluminum can bind to doxycycline and reduce its absorption in the gastrointestinal tract. This can significantly decrease the effectiveness of the antibiotic. To ensure optimal absorption, doxycycline should be taken on an empty stomach or with a full glass of water, and antacids should be avoided within 2 hours of taking the medication.

C. Obtain frequent eye checkups to prevent complications with this medication:
There is no evidence that doxycycline requires frequent eye checkups for the prevention of complications. While doxycycline can cause side effects like photosensitivity, gastrointestinal irritation, or, rarely, esophageal ulcers, eye exams are not routinely indicated unless the patient develops specific eye-related symptoms. This is not a priority teaching point for patients on doxycycline.

D. Avoid dairy products while taking this medication:
Dairy products, especially those containing calcium, should be avoided when taking doxycycline because calcium can bind to the antibiotic and reduce its absorption, making it less effective. To avoid this interaction, clients should not take doxycycline with dairy products or calcium supplements. It is important to space the administration of dairy products and doxycycline by at least 2 hours to ensure proper drug absorption and therapeutic efficacy.

A) Black-colored stools:
Black-colored stools are often a sign of gastrointestinal bleeding, particularly if the stool has a tarry appearance. This is not a common or expected side effect of rifampin. While rifampin can cause a variety of side effects, black stools are more commonly associated with gastrointestinal conditions or medications that irritate the stomach or gastrointestinal tract, such as iron supplements or nonsteroidal anti-inflammatory drugs (NSAIDs). Therefore, black stools should be investigated further and are not a typical reaction to rifampin.

B) Orange-colored secretions:
Rifampin is known to cause a harmless but notable side effect: the discoloration of bodily fluids, including urine, sweat, saliva, and tears, turning them a bright orange or red color. This is a well-known effect of the drug and is typically harmless, although it can be alarming for the patient. Patients should be instructed about this effect, especially for things like wearing contact lenses (which can be stained) and avoiding staining clothes. This is the most appropriate and expected clinical manifestation to inform the patient about.

C) Staining of teeth:
Staining of teeth is not a common side effect of rifampin. Although some antibiotics, such as tetracyclines, are associated with tooth discoloration (especially in children), rifampin is not known to cause staining of the teeth. This side effect is not typically seen in patients taking rifampin for tuberculosis or other infections.

D) Constipation:
Constipation is not a typical or common side effect of rifampin. While gastrointestinal side effects like nausea, vomiting, and abdominal discomfort can occur, constipation is not one of the expected reactions. Rifampin is more likely to cause digestive upset rather than constipation. If constipation occurs, it is more likely related to other factors such as diet, hydration, or other medications, rather than being directly caused by rifampin.