No, hydralazine does not usually lower heart rate. Its main action is to relax blood vessels and lower blood pressure. When the blood vessels widen, the body may respond by making the heart beat faster.
This response is called reflex tachycardia. It means the heart rate rises because the body is trying to keep enough blood moving through the body after blood pressure falls.
What Does Hydralazine Do to Heart Rate?
Hydralazine works mainly on the smooth muscle in blood vessel walls. It relaxes these vessels, making them wider and reducing resistance to blood flow.
As blood pressure drops, the body can sense the change. The nervous system may then increase the heart rate to help maintain blood flow.
So, while hydralazine lowers blood pressure, it can sometimes increase rather than decrease your pulse.
Why Can Hydralazine Make the Heart Beat Faster?
Your body tries to keep blood pressure and blood flow stable.
When hydralazine causes the blood vessels to relax, blood pressure may fall. In response, the body releases signals that increase heart activity. The heart may beat faster and pump more strongly for a short time.
This is the body’s natural response to a change in blood pressure. It is also one reason hydralazine may be used with another medicine when appropriate.
Can Hydralazine Cause a Fast Heart Rate?
Yes. A fast heartbeat or palpitations can occur with hydralazine.
You may notice that your heart feels like it is beating faster, harder, or more noticeably than usual. This can be more likely when starting treatment or when the dose is increased.
A fast heart rate does not always mean something dangerous is happening. Still, persistent or severe symptoms should be discussed with a healthcare professional.
Does Hydralazine Slow the Heart Down?
Hydralazine is not designed to slow the heart.
Medicines such as beta blockers work directly on certain signals that increase heart rate. Hydralazine works in a different way by relaxing blood vessels.
If a person taking hydralazine also needs heart-rate control, a healthcare professional may consider another medicine based on the person’s condition. Do not add or change heart medicines without medical guidance.
What Happens to Heart Rate When Blood Pressure Falls?
The heart and blood vessels work together to maintain blood flow.
When blood pressure drops, the body may respond by increasing the heart rate. This helps push more blood through the circulation.
That response can happen with hydralazine because of its blood vessel effects. The change in pulse is not the main purpose of treatment, but it can occur as the body adjusts.
Can Hydralazine Lower Blood Pressure Without Lowering Heart Rate?
Yes.
Hydralazine can reduce blood pressure without directly slowing the heart. Its main effect is to reduce resistance in the blood vessels.
Some people may have little change in heart rate, while others may develop a noticeable increase. The response depends on the dose, the person’s health, and other medicines being taken.
Why Might Hydralazine Be Combined With a Beta Blocker?
A healthcare professional may combine hydralazine with a beta blocker in certain situations.
Hydralazine relaxes blood vessels but can trigger reflex tachycardia. A beta blocker can help control the increase in heart rate caused by this response.
The combination is not suitable for everyone. The choice depends on the person’s blood pressure, heart rate, heart condition, and other medicines.
What If Your Heart Rate Changes After Taking Hydralazine?
Pay attention to both the number and how you feel.
A mild increase in pulse may occur as your body responds to lower blood pressure. If your heart rate stays unusually high, becomes irregular, or comes with dizziness, weakness, chest discomfort, or shortness of breath, contact a healthcare professional.
Keep a record of your blood pressure and pulse if you are asked to monitor them at home. This can help your healthcare professional see how you respond to treatment.
Do not stop hydralazine suddenly or change the dose because your pulse has changed unless you have been told to do so.
When Does a Fast Heart Rate Need Medical Attention?
A fast heart rate should not be ignored when it is severe, persistent, or accompanied by concerning symptoms.
Seek urgent medical care if you have a fast or irregular heartbeat with chest pain, severe shortness of breath, fainting, severe dizziness, or significant weakness.
For less urgent changes, contact your healthcare professional if your pulse remains higher than usual or you regularly notice strong or rapid heartbeats after taking hydralazine.
The Bottom Line
Hydralazine does not normally lower heart rate. It lowers blood pressure by relaxing blood vessels, and this can cause the body to respond with a faster heartbeat.
This reflex increase in heart rate is one of the important effects to consider when using hydralazine. If you notice a persistent or uncomfortable change in your pulse, speak with a healthcare professional rather than changing your dose yourself.
References
- Hydralazine drug information, uses, and side effects — MedlinePlus
- Hydralazine prescribing information and warnings — DailyMed
- Tachycardia: causes, symptoms, and treatment — Mayo Clinic
Medical Disclaimer
This content is for educational purposes and does not replace medical advice. Hydralazine should be taken only as prescribed. Contact a healthcare professional about significant changes in heart rate or concerning symptoms.