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Genital Herpes

Part of Herpesviridae Infections

1 published article · Updated continuously

Clinical Trial Landscape

Clinical Trials for Genital Herpes

10 trials tracked for Genital Herpes: 7 in phase 3 or 4 and 2 with published results. The most-cited published study has 126 citations.

10Trials tracked
7Phase 3 & 4
0Recruiting
2With published results
Phase distribution
Phase 4 5 Phase 3 2 Phase 2 1 Other / NA 2
  1. Phase 4 Randomized Trial to Evaluate Suppressive Effect of High-Dose Valacyclovir Versus Once-Daily Valacyclovir on Persons With HSV-2 Completed · 126 cited
  2. Phase 4 A Randomized Trial to Evaluated the Suppressive Effect of Acyclovir on Rapidly Cleared HSV-2 Reactivation Completed · 126 cited
  3. Phase 4 Trial to Study the Effect of Dose of Herpes Simplex Virus-2 (HSV-2) Suppressive Therapy on HSV and HIV Completed
  4. Phase 4 Patient-initiated Episodic Treatment of Recurrent Genital Herpes in Black Patients Completed
  5. Phase 4 Randomized Trial to Evaluate Suppressive Effect of High-Dose Acyclovir Versus Once-Daily Valacyclovir on Persons With HSV-2 Completed
  6. Phase 3 Efficacy of Oral Famciclovir 125mg Comparing to Aciclovir 200 mg Treatment in Patients With Active Recurrent Genital Herpes Completed
Show 4 more trials
  1. Phase 3 Efficacy and Safety of Famciclovir 1-day Treatment Compared to 3-day Treatment With Valacyclovir in Adults With Recurrent Genital Herpes Completed
  2. Phase 2 A Study of mRNA-1608, a Herpes Simplex Virus -2 (HSV-2) Therapeutic Candidate Vaccine, in Healthy Adults 18 to 55 Years of Age With Recurrent HSV-2 Genital Herpes Completed
  3. N/A GUD Clinical and Virologic Response to Acyclovir in HIV Negative African Women Completed
  4. N/A The VIBLOK SAfety and perFormancE Trial Completed

Showing the 10 most-cited and recently-updated of 10 trials. Browse the full registry →

Trial data sourced from ClinicalTrials.gov. Counts describe the research landscape and are not a treatment recommendation. Informational only — not medical advice.

What the trials found Updated — new results For clinicians

Genital Herpes: what the trials found

A phase 4 trial found that suppressive acyclovir significantly reduced HSV-2 genital shedding compared to no medication in both HIV-seronegative and HIV-seropositive individuals (per-day shedding rate: 24 vs. 3; p<0.001) 2. High-dose valacyclovir also significantly reduced shedding compared to once-daily valacyclovir (per-day shedding rate: 5 vs. 3; p<0.001) 3. However, high-dose acyclovir did not significantly reduce shedding compared to once-daily valacyclovir (per-day shedding rate: 4 vs. 4; p=0.052) 4. In a separate trial, valacyclovir 1 g twice daily significantly reduced HIV-1 RNA plasma levels compared to acyclovir 400 mg twice daily (4.08 vs. 3.68 log10 copies/mL; p<0.001), but no significant differences were observed in genital HSV shedding rate (8.2% vs. 7.8%; p=0.78) or percentage of days with genital herpes lesions (4.0% vs. 1.0%; p=0.16) 5.

In trials of famciclovir for genital herpes, one phase 4 trial found no significant difference in time to healing of non-aborted lesions compared to placebo (5.38 vs. 4.79 days; p=0.4161) and similar percentages of participants with aborted and non-aborted lesions (24.4% vs. 20.4% aborted; 75.6% vs. 79.6% non-aborted) 6. A phase 3 trial reported that 32.7% of participants on famciclovir had aborted lesions versus 33.6% on placebo 8. Another phase 3 trial (N=150) also evaluated famciclovir but no specific outcome data were provided 7.

Recent results — preliminary, needs further review

  • A phase 2 trial of mRNA-1608 (N=303) reported the number of genital herpes recurrence episodes per participant from 14 days after the second injection to 6 months: 1.4, 1.2, 1.3, and 1.0 across dose groups; and to 12 months: 2.8, 2.3, 2.5, and 1.8. Change from baseline in lesion rate (percentage of days with lesions) at 2 months after second injection was -7.75, -5.89, -10.70, and -5.84 1. These findings are recent and not yet corroborated.

For the clinician treating this condition

  • Suppressive acyclovir and high-dose valacyclovir significantly reduce HSV-2 genital shedding, but high-dose acyclovir was not superior to once-daily valacyclovir in reducing shedding.
  • Valacyclovir 1 g twice daily reduces HIV-1 RNA plasma levels more than acyclovir 400 mg twice daily, but does not significantly affect genital HSV shedding or lesion days.
  • Famciclovir did not show significant benefit over placebo in healing time or lesion abortion rates in the trials reviewed.

AI synthesis of 8 cited trials, updated Jun 29, 2026. Informational only — not medical advice; trial data sourced from ClinicalTrials.gov. How we use AI.

HCP Mode — summaries include clinical detail, trial data, and statistical outcomes.
Patient Mode — summaries use plain language, avoiding clinical jargon.

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