Byol - Use | Dose | Side Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Byol is a drug that belongs to a group of beta blockers. It works by blocking beta receptors in the heart and blocking the action of adrenaline. Therefore, it lowers blood pressure.

This medicine is used for the treatment of high blood pressure (hypertension) and mild heart failure. High blood pressure often goes without symptoms, but it is very important that your blood pressure is within normal limits in order to prevent heart attack and stroke.

It can be used to prevent attacks of angina pectoris and in the treatment of tachycardia (rapid heartbeat) because it slows down the heart rate.

You will need to make lifestyle changes too:

  • Exercise for at least half an hour during the day
  • Eat healthy diet based on fruits, vegetables and fish
  • Avoid fat in your diet
  • Stop smoking
  • Avoid stress


Byol should be avoided, or may be used, only with extra precautions in the following conditions:

  • Diabetes (diabetes mellitus). Byol can change individual symptoms of diabetes and makes it difficult for you to recognize them when glucose in your blood is low.
  • If you have trouble breathing (e.g. asthma, bronchitis). Byol may narrow the bronchi and make it harder to breathe.
  • Kidney or liver problems.
  • If you have circulation problems.
  • Thyroid gland disorders
  • Mental disorders such as depression
  • Myasthenia gravis (muscle disease)
  • If you have a slow heart rate (bradycardia) or atrioventricular block II or III degree. It may further slow the heart rate in these patients and cause cardiac arrest!
  • If you are allergic to Byol or other similar medications:
    • propranolol,
    • atenolol,
    • carvedilol,
    • labetalol,
    • sotalol,
    • metoprolol and others. Symptoms of an allergic reaction include:
      1. skin rash,
      2. redness,
      3. itching,
      4. swelling of the tongue,
      5. face and throat,
      6. difficulty breathing. If you are experiencing any of these symptoms, contact your doctor immediately.
  • If you are planning surgery, tell your doctor that you are taking Byol

Use during pregnancy and breastfeeding

Byol belongs to group C, according to the US Agency for Food and Drug Administration (FDA: Group C). This means that there are animal studies that have shown that it is harmful to the fetus in animals, but thus far, there have been no studies on humans. This medicine should be used during pregnancy only if the benefit to the mother outweighs the risk to the child.

It is not known whether Byol passes into breast milk. Avoid breastfeeding while using this drug.

Byol Use and Dose

Byol is usually used once a day. Make sure you are using it always at the same time of day.

The dose depends on the condition as a severity of the disease.

The dose ranges from 1.25 mg to 20 mg per day.

Dose reduction is required in patients with impaired liver or kidney function.

The usual initial dose in the therapy of hypertension is 5 mg per day, and it can be increased until desired effect is achieved.

It should be gradually tapered off. Your doctor will probably recommend to you to drink a smaller dosage for one week (for example, if you are taking 10 mg, then you will take 5 mg for the next 7 days), and for the next 7 days you will taking every other day. So, first you will take Byol in a smaller dose for 7 days, and then for the next 7 days you will take every other day. Then, you can completely stop using this drug.

If you suddenly stop using it, you might experience heart problems!

It should be taken with a glass of water always at the same time a day.

This medicament should not be used in combination with alcoholic beverages because they can hamper the effect of Byol.

During the treatment with this drug, you will often need to control your blood pressure.

Byol may cause orthostatic hypotension (a form of low blood pressure that happens when you stand up from sitting or lying down) causing dizziness and blackouts. Therefore, avoid getting up suddenly while using Byol.

You will need to make lifestyle changes too:

  • Exercise for at least half an hour during the day
  • Eat healthy diet based on fruits, vegetables and fish
  • Avoid fat in your diet
  • Stop smoking
  • Avoid stress


If you have taken more Byol than your doctor recommended, contact your doctor immediately.

Symptoms of an overdose include: slow heartbeat, shortness of breath, confusion, unconsciousness and seizures.

Use with other drugs (Interactions)

Byol should be avoided, or may be used only with extra precautions with the following medications:

  • If you are taking other medications that can slow the heart rate, such as:
    • verapamil,
    • diltiazem,
    • propranolol,
    • carvedilol,
    • labetalol,
    • metoprolol and others. Concomitant use of Byol with these medications can lead to cardiac arrest!
  • If you are using mediations used in the treatment of pain or arthritis such as:
    • ibuprofen,
    • ketoprofen,
    • naproxen,
    • diclofenac,
    • fenoprofen,
    • sulindac,
    • meloxicam,
    • piroxicam and others. These medications can increase the blood pressure, so concomitant use of these medications is not recommended.
  • Medications used in the treatment of diabetes (diabetes mellitus). Byol can change individual symptoms of diabetes and makes it difficult for you to recognize them when glucose in your blood is low! If your blood sugar drops below the limit, rapid heartbeat, you used to recognize low blood sugar will not appear.
  • Medications used in the treatment of asthma, such as:
    • albuterol,
    • terbutaline and others.

Tell your doctor about all medications and herbal preparations you are taking.

Side effects

The most dangerous side effect of Byol is a slow heartbeat (bradycardia). If you notice slow heartbeat, contact your doctor immediately.

Byol may narrow the bronchi (especially in patients with asthma and  patients suffering from bronchitis or emphysema) and make it harder to breathe. If you notice shortness of breath (e.g. whistling sound made while breathing, shortness of breath), contact your doctor immediately.

It can cause liver damage, which is manifested by increasing hepatic enzyme levels (AST, ALT).

Byol, like all other medications, can cause an allergic reaction. Symptoms of an allergic reactions include:

  • skin rash,
  • itching,
  • redness of the skin,
  • swelling of the tongue,
  • swelling of the face,
  • swelling of the throat,
  • difficulty breathing,
  • anaphylactic shock. An allergic reaction can be life threatening.

Other side effects of Byol are:

  1. fatigue,
  2. nausea,
  3. vomiting,
  4. constipation,
  5. diarrhea,
  6. insomnia,
  7. depression,
  8. hallucinations,
  9. anxiety,
  10. frequent urination,
  11. dry mouth,
  12. ringing in your ears,
  13. impotence,
  14. cold hands or feet and other symptoms.

This list is not complete. Tell your doctor if you are experiencing any side effects.

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.

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