Cialis is a prescription medicine taken by mouth for the treatment of erectile dysfunction (ED) in men. ED is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection. Cialis may help a man with ED get and keep an erection when he is sexually excited. Clinical studies show that Cialis works faster, lasts up to 36 hours and has less side effects than Viagra.

Cialis is used for:
Treating erectile dysfunction (ED). The active ingredient in Cialis is Tadalafil. Cialis is a phosphodiesterase inhibitor that works by helping to increase blood flow into the penis during sexual stimulation. This helps you to achieve and maintain an erection.

Do NOT use Cialis if:
• you are allergic to any ingredient in Cialis
• you have severe liver problems or certain hereditary degenerative eye problems (eg, retinitis pigmentosa)
• you have certain heart problems, low blood pressure, or uncontrolled high blood pressure
• you have had a heart attack within the past 90 days or a stroke within the past 6 months
• you are taking nitrates (eg, isosorbide, nitroglycerin) in any form (eg, tablet, capsule, patch, ointment) or nitroprusside
• you use certain recreational drugs called "poppers" (eg, amyl nitrate, butyl nitrate)
Contact your doctor or health care provider right away if any of these apply to you.

Before using Cialis:
Some medical conditions may interact with Cialis . Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
• 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 a deformed penis (eg, Peyronie disease, cavernosal fibrosis), blood problems (eg, sickle cell anemia, leukemia, multiple myeloma), or any other condition that may increase the risk of a prolonged erection (priapism)
• if you have a history of certain eye problems (eg, retinitis pigmentosa, sudden vision loss, optic neuropathy, macular degeneration)
• if you have a history of liver or kidney problems, dialysis, high or low blood pressure, ulcers, bleeding problems, blood vessel problems, heart problems (eg, heart failure, irregular heartbeat, aortic stenosis, angina), or blood vessel problems
• if you have a history of heart attack, stroke, or life-threatening irregular heartbeat
Some MEDICINES MAY INTERACT with Cialis . Tell your health care provider if you are taking any other medicines, especially any of the following:
• Alpha-blockers, medicines for high blood pressure, nitrates or nitroprusside because severe low blood pressure with dizziness, lightheadedness, and fainting may occur
• Azole antifungals (eg, itraconazole), HIV protease inhibitors (eg, ritonavir), macrolide antibiotics, because they may increase the risk of Cialis 's side effects
• Rifampin because it may decrease Cialis 's effectiveness
This may not be a complete list of all interactions that may occur. Ask your health care provider if Cialis may interact with other medicines that you take.

How to use Cialis:
Use Cialis as directed by your doctor. Check the label on the medicine for exact dosing instructions.
• Take Cialis by mouth with or without food.
• Cialis may be taken up to 36 hours before sexual activity, as directed by your doctor.
• Do not take Cialis more often than once daily, or as directed by your doctor.
• Check with your doctor before you eat grapefruit or drink grapefruit juice while you are taking Cialis.
• If you miss a dose of Cialis and you still intend to engage in sexual activity, take it as soon as you remember. Continue to take it as directed by your doctor.
Ask your health care provider any questions you may have about how to use Cialis.

Important safety information:
• Cialis may cause dizziness, drowsiness, fainting, or blurred vision. These effects may be worse if you take it with alcohol or certain medicines. Use Cialis with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it.
• Do not drink large amounts of alcohol while you take Cialis . Doing so may increase your risk of dizziness, headache, fast heartbeat, and low blood pressure.
• Patients with heart problems who take Cialis may be at increased risk for heart-related side effects, including heart attack or stroke.
• Cialis may rarely cause a prolonged, painful erection. Contact your doctor right away if this happens.
• Do not use other medicines or treatments for erectile dysfunction while you are taking Cialis.
• Cialis does not stop the spread of HIV or other sexually transmitted diseases (STDs) to others through sexual contact. Use barrier methods of birth control (eg, condoms) if you have HIV infection or an STD.
• Cialis will not prevent pregnancy. If your partner may become pregnant and you wish to avoid pregnancy, be sure to use an effective form of birth control.

Possible side effects of Cialis:
All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:
• Dizziness; flushing; headache; heartburn; mild back or muscle pain; stomach upset; stuffy or runny nose.
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); chest pain; fainting; fast or irregular heartbeat; prolonged, painful erection; red, swollen, blistered, or peeling skin; ringing in the ears; severe or persistent back or muscle pain; severe or persistent vision changes; sudden decrease or loss of vision in one or both eyes; sudden hearing loss.
If you have questions or need medical advice about side effects, contact your doctor or health care provider.

Proper storage of Cialis:
Store Cialis at 77 degrees F (25 degrees C). Brief storage at temperatures between 59 and 86 degrees F (15 and 30 degrees C) is permitted. Store away from heat, moisture, and light. Do not store in the bathroom. Keep Cialis out of the reach of children and away from pets.