An elevated heart rate and blood pressure changes are common during withdrawal — usually not dangerous on their own, but worth understanding.
Why it happens: Opioids suppress activity in the part of the nervous system responsible for the “fight or flight” response. Withdrawal removes that suppression, producing a rebound increase in heart rate and blood pressure.
When this is a bigger concern: If you have an existing heart condition, uncontrolled high blood pressure, or are older, this symptom is worth mentioning to a doctor before attempting withdrawal, since the added cardiovascular strain matters more with those conditions present. "is withdrawal dangerous" article
What tends to help: This symptom generally isn’t managed directly, but staying hydrated and avoiding stimulants (including excess caffeine) during this window can help avoid compounding it.
Medically reviewed by [pending]. Source: SAMHSA TIP 63.