The purpose of this study is to test the potential benefits of BHV-7000 in reducing chronic pain in participants with IEM with a previously demonstrated gain of function mutation in the SCN9A gene.

Key Inclusion Criteria:

1. Adult men and women between 18 to 75 years of age, inclusive, at time of consent with a diagnosis of inherited erythromelalgia with a previously characterized gain of function NaV1.7 mutation resulting in chronic pain.
2. Absence of concomitant mutation resulting in Kv7.2/7.3 gain of function.
3. Ability and willingness to adhere to the study procedures and complete accurate pain diaries
4. Stable background analgesic regimen for at least 30 days before screening and willingness to maintain the same analgesic regimen during the study period.

Key Exclusion Criteria:

1. Any clinically significant laboratory abnormalities or clinically significant abnormalities on screening physical examination, vital signs, or ECG that, in the judgment of the principal investigator, indicates a medical problem that would preclude study participation.
2. Any medical condition, based on the judgement of the Investigator, that would confound the ability to adequately assess safety and efficacy outcome measures