Relájate y Rejuvenece: Los Beneficios de Belleza de un Baño con Sales de Epsom  

(Alternatively, for a slightly more natural flow in Spanish, you could say: "Relájate y Recupérate: Los Beneficios Estéticos de un Baño con Sales de Epsom")  

Both versions are correct—the first emphasizes "beauty benefits" directly, while the second uses "estéticos" (aesthetic) for a nuanced tone. The name "Epsom salt" is commonly translated as "sales de Epsom" or "sales de Epsom salt" in Spanish, though some regions may simply use "sales de magnesio" (magnesium salts).  

Would you like any adjustments for a specific regional audience?