[Question #11520] Herpes and Valtrex
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13 months ago
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Can valtrex cover an old herpes infection of a year or so on an STD test, as in give you a false negative? Or does it only impact new infections?
If the infection is new and it does impact the test results. How many doses of valtrex would that be to have a false negative test?
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Terri Warren, RN, Nurse Practitioner
13 months ago
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No, the concern about the use of Valtrex is immediately after a new infection that could cause a false negative. Taking Valtrex for longer than a couple of weeks may well influence an antibody test.
Terri
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13 months ago
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Thank you for your answer.
Do you mind explaining the science behind it?
How Valtrex interferes herpes antibodies being built but not antibodies that are already created?
Thank you
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Terri Warren, RN, Nurse Practitioner
13 months ago
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If someone takes antivirals right at the beginning of a new infection for an extended period of time, and it is working well (stopping viral replication), then your immune system cannot see the virus and cannot make antibody in response. So a test done in that person could yield a false negative. However, once antibody has been made in a person with long standing infection, taking the medication does not take the antibody away.
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Terri
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13 months ago
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false positive? I thought Valtrex could give you a false negative?
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Terri Warren, RN, Nurse Practitioner
13 months ago
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Thanks for catching that error, yes, false negative, and I fixed that in my response to you.
Terri
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13 months ago
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So an individual taking Valtrex with an old infection should show up positive?
Would an individual taking Valtrex with no infection test be impacted?
This is a scenario in which an individual knows, they have hsv1 and is taking Valtrex for that condition that they have had for years, but wants to get a routine std test.
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Terri Warren, RN, Nurse Practitioner
13 months ago
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Yes, an individual with an old infection should show up positive on a western blot (the IgG test misses 8% of HSV 2 infections and 30% of HSV 1 infections)
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Taking Valtrex would not impact an individual who is not infected with either type of HSV, correct
HSV testing is not recommended with a routine STI screening due to the high rate of false positives for HSV 2.
Terri