SIDE EFFECTS: See also Warning and Precautions sections. Tiredness, slow heartbeat, and dizziness may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. To lower your risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position. This drug may reduce blood flow to your hands and feet, causing them to feel cold. Smoking may worsen this effect. Dress warmly and avoid tobacco use. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if any of these unlikely but serious side effects occur: very slow heartbeat, severe dizziness, fainting, blue fingers/toes, trouble breathing, new or worsening symptoms of heart failure (such as shortness of breath, swelling ankles/feet, unusual tiredness, unusual/sudden weight gain), mental/mood changes (such as confusion, mood swings, depression). A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking penbutolol, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: certain types of heart rhythm problems (such as a slow heartbeat, second- or third-degree atrioventricular block), severe heart failure, breathing problems (such as asthma, chronic bronchitis, emphysema). Before using this medication, tell your doctor or pharmacist your medical history, especially of: treated stable heart failure, kidney disease, liver disease, overactive thyroid disease (hyperthyroidism), serious allergic reactions including those needing treatment with epinephrine, blood circulation problems (such as Raynaud's disease, peripheral vascular disease), mental/mood disorders (such as depression), a certain muscle disease (myasthenia gravis). If you have diabetes, this product may mask the fast/pounding heartbeat you would usually feel when your blood sugar falls too low (hypoglycemia). Other symptoms of low blood sugar, such as dizziness and sweating, are unaffected by this drug. This product may also make it harder to control your blood sugar. Check your blood sugar regularly as directed and share the results with your doctor. Tell your doctor right away if you have symptoms of high blood sugar such as increased thirst/urination. Your doctor may need to adjust your diabetes medication, exercise program, or diet. Before having surgery, tell your doctor or dentist that you are taking this medication. This drug may make you dizzy. Alcohol or marijuana can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana. Kidney function declines as you grow older. This medication is removed by the kidneys. Therefore, older adults may be more sensitive to the side effects of this drug, including dizziness and tiredness. During pregnancy, this medication should be used only when clearly needed. It may harm an unborn baby. Discuss the risks and benefits with your doctor. It is unknown if this medication passes into breast milk or if it may harm a nursing infant. Discuss the risks and benefits with your doctor before breast-feeding.

DRUG INTERACTIONS: See also Precautions section. Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor or pharmacist first. Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: fingolimod. Some products have ingredients that could raise your heart rate or blood pressure. Tell your pharmacist what products you are using, and ask how to use them safely (especially cough-and-cold products, diet aids, or NSAIDs such as ibuprofen/naproxen). This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: very slow heartbeat, severe dizziness, severe weakness, fainting, trouble breathing.