High frequency contraindications

I am looking into High Frequency and it has standard contraindications that make sense like pace makers, epilepsy, pregnancy and so on, what I’d like clarified is why exactly it says people with blood pressure issues should not use it? Can they use it if on medication? Do you just use the lowest level for them? Is there an actual concern with the frequency affecting blood pressure somehow? Is it specifically people with high blood pressure or low blood pressure that should not use or both?