Nearly a decade and a half after its 2003 approval by the U.S. Food and Drug Administration, Cialis remains one of the world’s best-selling medications designed to treat erectile dysfunction. Tadalafil, the drug’s active ingredient, was specifically developed to treat erection problems caused by insufficient blood flow to the penis, which is estimated to be responsible for the vast majority of male impotence worldwide.

If you are experiencing increased difficulties in getting and keeping an erection hard and long-lasting enough for sexual penetration, Cialis might very well be the drug for you. However, before you seek a prescription for the drug, here are a few important things you need to know about the medication:

1. It’s a PDE5 Inhibitor

Tadalafil, the active ingredient in Cialis, belongs to a family of drugs known collectively as PDE5 inhibitors, so-called for their unique ability to temporarily disable an enzyme known as phosphodiesterase-5, which can interfere with optimal blood flow to the penis. If your erection problems are associated with vascular insufficiency, it’s likely that Cialis will give you the help you need to regain — at least temporarily — normal Erectile Function.

If, however, you suspect that your ED symptoms are more likely to be caused by psychological problems, such as depression or extreme anxiety, it’s unlikely that Cialis will get you back in the game. Nor will the drug be of any help to those men whose erectile function has been impaired through traumatic injury to the male genitals. For the latter problem, you’ll probably need some sort of surgical intervention, while psychological obstacles to Normal Erectile Function can best be addressed with the help of a psychologist or other qualified mental counselor.

2. There are Two Formulations 

Cialis is the only ED drug that’s available in two different formulations — one that can be taken daily to ensure you’ll be ready for sexual activity whenever the need arises and another that’s to be used only as needed. Both versions of Cialis contain the same active ingredient, but each has its own unique dosage strengths to accomplish the specific goals promised in Cialis’s advertising for each formulation.

Daily Cialis is available in tablets of 2.5 and 5 milligrams each. Once you’ve determined the strength needed to maintain round-the-clock erectile function, you will take one tablet daily for as long as you seek to maintain that state of readiness. Cialis for use as needed is available in tablets of 10 and 20 milligrams each. As its name implies, it is taken 15 to 60 minutes before sexual activity is expected to begin.

3. The ‘Weekend Pill’

Cialis for use as needed has been nicknamed the “weekend pill” because its extended duration of action — up to 36 hours — can conceivably restore normal erectile function to a user from late on Friday until sometime early Sunday morning. The lasting power of all other PDE5 inhibitors, including Viagra, Levitra, Staxyn, and Stendra, ranges from four to six hours, based on their advertising.

4. Talking with Your Doctor

Even before your partner shares her concerns, you will undoubtedly be the first to recognize a worrisome decline in erectile function. If you suspect that your erection problems are related to blood flow, as most are, then it’s time to speak frankly with your doctor. Cialis, like all other ED drugs now on the market, can only be purchased with a prescription.

To help document the nature and frequency of your problems, consider keeping track of your erection difficulties so that you can accurately report to the doctor what’s been going on downstairs. If the doctor believes that your symptoms of impotence are likely being caused by vascular insufficiencies, he or she will almost certainly provide a prescription so that you can purchase the PDE5 inhibitor of your choice. If the properties of one Cialis formulation appeal to you more, be sure to tell the doctor which drug you’d prefer.

Your doctor is probably the one person most familiar with your past medical history and the current medications you are taking. Because these factors can have a bearing on the advisability of using Cialis — or any other PDE5 inhibitor — your doctor is the best counselor you’re likely to find on this matter.

5. Cialis Is Not for Everyone

All PDE5 inhibitors can have side effects, most of which are relatively mild and often disappear altogether upon continued use. However, certain pre-existing medical conditions may indicate that you are not an appropriate candidate for Cialis or any other PDE5 inhibitor.

Such medical conditions may include, but are not limited to, heart problems, such as angina, heart failure, or irregular heart rhythms; intractable low blood pressure; stroke; pulmonary hypertension; certain kidney or liver problems; and an eye condition known as retinitis pigmentosa. Other medical problems that may make it unwise to use Cialis include certain severe vision problems, such as NAION (Non-Arteritic Anterior Ischemic Optic Neuropathy); bleeding problems, such as stomach ulcers; and blood cell problems, such as leukemia, multiple myeloma, and sickle cell anemia.

6. Possible Drug Interactions

Cialis and all other PDE5 inhibitors work their magic by temporarily lowering central blood pressure. Taking these drugs with any other drugs that also lower blood pressure can be extremely dangerous, even life-threatening. These ED drugs should never be taken concurrently with nitrate-based drugs which also depress blood pressure sharply.

Other medications known to interact adversely with Cialis include alpha-blockers, such as those prescribed for prostate problems; certain blood pressure drugs; HIV medications; oral antifungal drugs; some antibiotics; certain antihistamines; and drugs known as guanylate cyclase stimulators that are prescribed for the treatment of pulmonary arterial hypertension.

7. Adverse Side Effects

Common side effects of Cialis include back pain, flushing, headache, indigestion, muscle pain, and runny or stuffy nose. As previously noted, these side effects are generally mild and often disappear shortly after the drug’s been taken. More serious side effects include a sudden decrease or loss of hearing or vision and an erection that lasts for more than four hours. If you should experience these more serious side effects, seek medical attention immediately.

If you’d prefer to order Cialis or any other PDE5 inhibitor online, consider using eDrugstore.com, one of the Internet’s most reliable suppliers of prescription and over-the-counter drugs and healthcare products. If you already have a prescription from your doctor, you can fax or scan and email it along with your order. If not, eDrugstore can arrange an online consultation with one of its team of licensed U.S. doctors. To get started, click below to access eDrugstore’s ED Medication Guide.