Everyone has seen the proliferation of TV commercials – you know, the ones that have been particularly attractive to senior men who have lost one of life’s great pleasures.

I’m talking about the flood of TV pitches for the two major drugs for erectile dysfunction (ED), Viagra and Cialis.

Millions of men have tried one or both of these drugs with apparent satisfaction. The commercials do include warnings. Mainly, don’t take these drugs if you also take nitrates, and see a doctor immediately if an erection lasts more than four hours, say the commercials.

The emphasis, however, should be to see a doctor, preferably a urologist, before taking Viagra or Cialis. Both Viagra and Cialis cause the muscles that control the blood vessels to relax. As a result, your blood pressure drops. Lowering blood pressure decreases the flow of blood to the heart, which can precipitate a heart attack.

The Food and Drug Administration (FDA) has warned that neither of these drugs for impotence should be taken if you also take medications that include nitrates in their ingredients.

Identifying a nitrate is no small task. There are more than 20 prescription forms of nitrate, including many which seniors take, ranging from eye drops for glaucoma to amlodipine, used to treat high blood pressure.

The generic name for Viagra is tadalafil. PubMed Health, a service of the National Library of Medicine, says, “You should know that the drug does not prevent pregnancy or the spread of sexually transmitted diseases…” You probably knew this. Before taking tadalafil, “ask your pharmacist for a list of the ingredients,” PubMed advises.

PubMed also counsels, “Tell your doctor if you have taken nitrates such as Isordil, Imdur, ISMO and Nitro-bid, Nitro-Dur, Nitroquick, Nitrostat, and what nonprescription medications, nutritional supplements and vitamins you are taking. Be sure to mention “any alpha blockers, certain anti-fungals, HIV protease inhibitors, Flomax, Zoloft, St. John’s Wort, medications for high blood pressure, diabetes, low blood pressure, an inherited eye condition that can cause loss of vision, or if you are having surgery, including dental surgery.

Nitrates come in a variety of forms: as tablets, sprays, patches, pastes, and ointments.

WebMed warns that “Many websites that claim to sell Viagra are selling illegal fake pills, which can be dangerous to your health. In fact, a recent study by the National Association of Boards of Pharmacy showed that only 4 percent of 7,000 sites reviewed are potentially legitimate.”

The only way you can buy real Viagra is with a prescription. The FDA has never approved the so-called “generic Viagra” that you may see for sale online. In fact, it’s against the law.

WebMed explains that inside a counterfeit pill you may be getting inadequate medication, or none at all — leaving your condition untreated. Or you may get too much medication, which can hurt you. You may get an ingredient, which causes dangerous interactions with other medications you take.

Some of the contents that have been found in counterfeit Viagra include amphetamines, sometimes known as speed; Metronidazole, an antibiotic that can bring on vomiting and diarrhea; and blue ink to give the pills the proper color of real Viagra.

In rare instances, men taking any erectile dysfunction medication have reported a sudden loss of vision or hearing. The most common side effects, as you’ve heard in the TV commercials are headaches, facial flushing, upset stomach and blurred vision.

While ED medications have brought joy and satisfaction to many, you need to follow the advice and heed the warnings that have been given.

You probably know that neither Viagra nor Cialis cures erectile dysfunction. And neither creates sexual desire. You have to have that as a starter.

Tait Trussell is an old guy and fourth-generation professional journalist who writes extensively about aging issues among a myriad of diverse topics.

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