If approved, the provider will issue a prescription. Cialis is also highly effective in reducing the symptoms of BPH. There are many safe, reliable online services offering ED prescriptions. In addition, consider the information below. Alternatively, Cialis may be prescribed as an as-needed treatment for ED, to be taken before sexual activity. Common ones include: Flushing of the skin.Viagra, Cialis, Levitra, and Stendra can help a person get and maintain an erection. Learn about the similarities and differences between these medications. Tadalafil (Cialis) is taken by mouth either as needed before sexual activity or once daily for erectile dysfunction (ED).It’s also taken once daily to treat symptoms from an enlarged prostate (benign prostatic hyperplasia, or BPH).Tadalafil (Cialis) is available both as brand-name and generic tablets. Common side effects of this medication include . The dose of Cialis you need will depend on whether you’re taking it daily or as needed. Daily doses are often between and 5 milligrams (mg). The as-needed dose is usually 10 mg but can range from 5–20 mg. The typicaldose of Viagra is 50 mg. However, the dosage can range from 25– mg.