• you are allergic to any ingredient in Glucotrol XL
• you have certain severe problems associated with diabetes (eg, diabetic ketoacidosis, diabetic coma)
• you have moderate to severe burns, or very high blood acid levels (acidosis)
• you have type 1 diabetes
• you are pregnant and are within 1 month of the expected delivery date.

Contact your doctor or health care provider right away if any of these apply to you.

Some medical conditions may interact with Glucotrol XL. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

• if you are pregnant, planning to become pregnant, or are breast-feeding
• if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
• if you have allergies to medicines, foods, or other substances
• if you have had a severe allergic reaction (eg, a severe rash, hives, breathing difficulties, dizziness) to any other sulfonamide medicine, such as acetazolamide, celecoxib, certain diuretics (eg, hydrochlorothiazide), probenecid, sulfamethoxazole, valdecoxib, or zonisamide
• if you have a history of liver, kidney, thyroid, or heart problems
• if you have stomach or bowel problems (eg, stomach or bowel narrowing or blockage, stomach paralysis), drink alcohol, or have had poor nutrition
• if you have very poor health, a high fever, a severe infection, severe diarrhea, or high blood acid levels, or have had a severe injury
• if you have a history of certain hormonal problems (eg, adrenal or pituitary problems, syndrome of inappropriate secretion of antidiuretic hormone [SIADH]), or low blood sodium levels
• if you have a condition called glucose 6-phosphate dehydrogenase (G6PD) deficiency
• if you will be having surgery.

Some medicines may interact with Glucotrol XL. Tell your health care provider if you are taking any other medicines, especially any of the following:

• Beta-blockers (eg, propranolol) because the risk of low blood sugar may be increased. They may also hide certain signs of low blood sugar and make it more difficult to notice
• Angiotensin-converting enzyme (ACE) inhibitors (eg, enalapril), anticoagulants (eg, warfarin), azole antifungals (eg, miconazole, ketoconazole), chloramphenicol, clofibrate, fenfluramine, insulin, monoamine oxidase (MAO) inhibitors (eg, phenelzine), nonsteroidal anti-inflammatory medicines (NSAIDs) (eg, ibuprofen), phenylbutazone, probenecid, quinolone antibiotics (eg, ciprofloxacin), salicylates (eg, aspirin), or sulfonamides (eg, sulfamethoxazole) because the risk of low blood sugar may be increased
• Calcium channel blockers (eg, diltiazem), corticosteroids (eg, prednisone), decongestants (eg, pseudoephedrine), diazoxide, diuretics (eg, furosemide, hydrochlorothiazide), estrogens, hormonal contraceptives (eg, birth control pills), isoniazid, niacin, phenothiazines (eg, promethazine), phenytoin, rifamycins (eg, rifampin), sympathomimetics (eg, albuterol, epinephrine, terbutaline), or thyroid supplements (eg, levothyroxine) because they may decrease Glucotrol XL's effectiveness, resulting in high blood sugar
• Gemfibrozil because blood sugar may be increased or decreased.

This may not be a complete list of all interactions that may occur. Ask your health care provider if Glucotrol XL may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

 Important safety information:

• Glucotrol XL may cause drowsiness, dizziness, blurred vision, or lightheadedness. These effects may be worse if you take it with alcohol or certain medicines. Use Glucotrol XL with caution. Do not drive or perform other possible unsafe tasks until you know how you react to it.
• Do not drink alcohol while you are taking Glucotrol XL. It may increase the risk of low blood sugar. Rarely, alcohol may interact with Glucotrol XL and cause a serious reaction with symptoms such as flushing, nausea, vomiting, dizziness, or stomach pain. Discuss any questions or concerns with your doctor.
• Carry an ID card at all times that says you have diabetes. Check your blood sugar levels as directed by your doctor. If they are often higher or lower than they should be and you take Glucotrol XL exactly as prescribed, tell your doctor.
• Proper diet, regular exercise, and regular blood sugar testing are important for best results with Glucotrol XL. Follow the diet and exercise program given to you by your health care provider.
• It may be harder to control your blood sugar during times of stress, such as fever, infection, injury, or surgery. Talk with your doctor about how to control your blood sugar if any of these occur. Do not change the dose of your medicine without checking with your doctor.
• Glucotrol XL may cause low blood sugar levels. Low blood sugar may make you anxious, sweaty, weak, dizzy, drowsy, or faint. It may also make your heart beat faster; make your vision change; give you a headache, chills, or tremors; or make you more hungry. It is a good idea to carry a reliable source of glucose (eg, tablets or gel) to treat low blood sugar. If this is not available, you should eat or drink a quick source of sugar like table sugar, honey, candy, orange juice, or non-diet soda. This will raise your blood sugar level quickly. Tell your doctor right away if this happens. To prevent low blood sugar, eat meals at the same time each day and do not skip meals.
• Risk of low blood sugar may be increased by severe or prolonged exercise, drinking alcohol, or skipping meals.
• Glucotrol XL is a sulfonylurea. It may increase the risk of death from heart disease. Talk with your doctor about the benefits and risks of this or other therapies to treat your condition.
• You may notice the tablet shell in your stool with some brands of Glucotrol XL. This is normal and not a cause for concern.
• Glucotrol XL may cause you to become sunburned more easily. Avoid the sun, sunlamps, or tanning booths until you know how you react to Glucotrol XL. Use a sunscreen or wear protective clothing if you must be outside for more than a short time.
• Tell your doctor or dentist that you take Glucotrol XL before you receive any medical or dental care, emergency care, or surgery.
• Lab tests, including fasting blood glucose and hemoglobin A_1c, may be performed while you use Glucotrol XL. These tests may be used to monitor your condition or check for side effects. Be sure to keep all doctor and lab appointments.
• Use Glucotrol XL with caution in the elderly; they may be more sensitive to its effects, especially low blood sugar levels.
• Glucotrol XL should not be used in children; safety and effectiveness in children have not been confirmed.
• Pregnancy and breast-feeding: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using Glucotrol XL while you are pregnant. Glucotrol XL should not be used for at least 1 month before the expected delivery date because it may cause low blood sugar in the baby. It is not known if Glucotrol XL is found in breast milk. Do not breast-feed while taking Glucotrol XL.

When used for long periods of time, Glucotrol XL may not work as well. If your blood sugar has been under control and then becomes hard to manage, contact your doctor. Do not change the dose of your medicine without checking with your doctor.

Check with your doctor if any of these most common side effects persist or become bothersome:

Diarrhea; dizziness; gas; nausea.

Seek medical attention right away if any of these severe side effects occur:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue; skin redness; dizziness); confusion; dark urine; fainting; fever, chills, or persistent sore throat; irregular heartbeat; low blood sugar symptoms (eg, anxiety, drowsiness, fast heartbeat, headache, lightheadedness, severe or persistent dizziness, tremors, unusual sweating, weakness); severe or persistent blurred vision or other vision problems; unusual bruising or bleeding; unusual tiredness or weakness; yellowing of the eyes or skin.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.