Yes. Certain people should not take valacyclovir and others should use decreased doses of valacyclovir. Below are some important examples.
Sensitivity or Allergies: Patients with sensitivity or an allergy to any of the following medications should not use Valacyclovir: Acyclovir, Famciclovir, ganciclovir, penciclovir, valacyclovir, or valganciclovir.
Kidney Issues: Dose adjustments should be made for those with kidney impairment or issues. Decreased doses are needed as kidney impairment slows the clearing from the body of valacyclovir. The degree of impairment determines the decrease in the dosage. The PDR states, “Acute renal failure and CNS (Nervous System) toxicity have been reported in patients with underlying renal (Kidney) dysfunction who have received inappropriately high doses of valacyclovir for their level of renal (Kidney) function. Patients receiving potentially nephrotoxic (Toxic to the Kidney) drugs together with valacyclovir may have an increased risk of renal dysfunction (impairment).”
The Elderly: The elderly are more likely to have impaired kidneys so they might not clear valacyclovir from their system as efficiently as they should. This can lead to inappropriately high levels of valacyclovir, which means the elderly may need lower doses of valacyclovir. The elderly are also more likely to experience neurological side effects, including: agitation, hallucinations, confusion, delirium, and other abnormalities of brain function termed encephalopathy.
Dehydration: When patients are dehydrated acyclovir can reform as a solid in the kidney leading to kidney damage. Patients should all remain well hydrated when taking valacyclovir.
Pregnancy: While a registry that collected data on the 756 pregnancies of women exposed to acyclovir in the first trimester showed no greater occurrence of birth defects than occurs in the general population, the study size was too small to guarantee safety during pregnancy.
You should not take Valacyclovir if you are pregnant or trying to become pregnant unless recommended by your obstetrician/gynecologist or other healthcare provider.
Breastfeeding: The PDR states, “According to the manufacturer, valacyclovir should be administered to a nursing mother with caution and only when indicated. Although the American Academy of Pediatrics (AAP) has not specifically evaluated valacyclovir, systemic maternal acyclovir is considered to be usually compatible with breastfeeding…Consider the benefits of breastfeeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition.”
See here for other special groups, warnings, and precautions
