Sexual activity may be a strain on your heart, especially if you have heart disease. You should only be treated with one of these products at a time. Your doctor will probably tell you not to take tadalafil if you are taking nitrates. Other uses for this medicine This medication may be prescribed for other uses; ask your doctor or pharmacist for more information. Take tadalafil at around the same time every day. Cialis is not recommended for people taking any form of nitroglycerin because the combination may lower blood pressure to an unsafe level. What important information should you know about Cialis?Cialis lasts up to 36 hours in the body, while Viagra lasts 4–6 hours in the body. Both are taken 30 minutes before sex. Cialis can cause limb pain, while Viagra can cause vision change, rash. MNT ‘s review. Lemonaid sells Cialis in these forms: Cialis: available in doses of 5, 10, and 20 mg, starting at $65 per tablet. Daily Cialis: 5 mg tablet with pricing starting from $50 per tablet. Hims offers brand name Cialis as a monthly supply of 5-mg tablets that can be taken daily. Generic Cialis (tadalafil) is available in mg, 5-mg, mg, mg, and mg tablets for daily or as.