Can I take valacyclovir (antiviral medication) with my calcium supplement?

Valacyclovir and Calcium Supplements: Drug Interaction Assessment

Valacyclovir can be safely taken with calcium supplements as there is no documented interaction between these medications. 1

Valacyclovir Overview

• Valacyclovir is an antiviral medication that is a prodrug of acyclovir, used to treat herpes simplex virus (HSV) infections, herpes zoster (shingles), and varicella zoster virus (VZV) infections 2
• Common dosing regimens include:
  • 500 mg to 1000 mg twice daily for genital herpes treatment 3
  • 1000 mg three times daily for 7 days for herpes zoster 4
  • 500 mg daily for suppressive therapy of recurrent genital herpes 1

Calcium Supplements Overview

• Calcium supplements are commonly available as calcium carbonate (40% elemental calcium) or calcium citrate (21% elemental calcium) 1
• Recommended daily calcium intake is 1000-1200 mg for adults, with upper intake levels of 2000-2500 mg per day 1
• Calcium supplements are best absorbed when taken with meals, particularly calcium carbonate which requires stomach acid for optimal absorption 1

Drug Interaction Analysis

• The CDC/NIH guidelines for opportunistic infections in HIV-infected adults do not list any interaction between valacyclovir and calcium supplements 1
• The table of drug interactions in the Guidelines for Management of Chronic Kidney Disease in HIV-infected patients lists interactions between quinolone antibiotics and calcium products, but does not mention any interaction with valacyclovir 1
• Calcium supplements are not listed among medications that affect valacyclovir absorption or metabolism 1

Important Considerations

Renal Function

• Valacyclovir is primarily excreted by the kidneys and can cause renal impairment through crystalluria in some cases 1
• Dose adjustment is necessary for patients with impaired renal function:
  • For creatinine clearance <30 mL/min, valacyclovir dosage should be reduced to 500 mg every 24-48 hours 1
  • Adequate hydration is important when taking valacyclovir to minimize risk of nephrotoxicity 1

Administration Timing

• Unlike some medications (such as quinolone antibiotics), valacyclovir does not form chelation complexes with calcium 1
• There is no recommendation for separating the timing of valacyclovir and calcium supplement administration 1

Special Populations

• For immunocompromised patients, higher doses of valacyclovir may be required, but this does not affect compatibility with calcium supplements 5
• For patients with ocular herpes, higher doses of valacyclovir (500 mg three times daily) may be recommended, without restrictions regarding calcium intake 1

Practical Recommendations

• Take valacyclovir as prescribed by your healthcare provider, typically twice daily for treatment or once daily for suppression 3, 2
• Take calcium supplements with meals for optimal absorption, particularly calcium carbonate 1
• Maintain adequate hydration while taking valacyclovir to reduce risk of renal adverse effects 1
• If you experience any unusual side effects, contact your healthcare provider 1

Monitoring

• No special monitoring is required when taking valacyclovir with calcium supplements unless you have substantial renal impairment 1
• For patients with renal impairment receiving high-dose valacyclovir, monitoring of renal function is recommended 1