Fixed drug eruptions can occur in the genital region, but the patient had neither bullous nor ulcerated eruptions (as one would expect with this condition). Fixed drug eruptions are usually hyperpigmented and require a history of taking medication, such as an antibiotic or a nonsteroidal anti-inflammatory drug.
Questions that help narrow the differential. Zeroing in on the cause of a patient’s genital lesions requires that you ask whether the lesions are painful, if the patient has dysuria, if there are any constitutional symptoms, and if this has happened before. Other distinguishing factors include enlarged lymph nodes and the presence of multiple (vs single) lesions.
Viral cell cultures are the preferred lab test
Common laboratory tests to make the diagnosis include viral culture, direct fluorescence antibody (DFA), polymerase chain reaction (PCR), and type-specific serologic tests.
Viral cell culture is the preferred test for suspected HSV of the skin and mucous membranes.2 PCR is the preferred test for suspected herpes meningitis or encephalitis when cerebrospinal fluid has been obtained through lumbar puncture.3 DFA and herpes culture can be ordered simultaneously. DFA can provide a quick result, and herpes culture can provide a more sensitive result (this may take 5-7 days before results are available).
No evidence that antivirals pose risk during pregnancy
Treatment with antivirals (acyclovir, famciclovir, or valacyclovir) may help to reduce the length of the outbreak. Oral antivirals are usually sufficient for uncomplicated HSV; IV antivirals may be needed in complicated cases. The current recommendation for acyclovir (the most commonly prescribed drug for HSV infection) is 400 mg 3 times daily or 200 mg 5 times daily for 7 to 10 days in a primary outbreak.3
Antiviral therapy is most effective if begun within 72 hours of symptom onset in primary herpes genitalis.4 Analgesics can help with pain control and sitz baths are helpful for women with severe dysuria.