DEAR DR. ROACH: I am an 80-year-old man who still has psychological drive, but who has lost the physical ability for an erection. Is there any safe way to restore this? I have had multiple bypass surgeries, so I am fearful of medicines like Viagra or Cialis, but I wonder about the safety of testosterone. — F.E.D.

ANSWER: Although older men often have decreasing ability for an erection, finding out the underlying cause is important before trying medications. In men with a known history of blockages in the artery — whether in the heart (leading to a stent or bypass), brain (leading to stroke or TIA) or elsewhere in the body (claudication, painful calf muscles with walking is a common symptom) — it is worth considering whether the arteries that supply the penis with blood flow might also be blocked. This might require specific treatment. In men without known blockages, erectile dysfunction is a clue that there might be arterial disease and should always be considered.

Treatment with sildenafil (Viagra) or similar drugs is usually safe in people with heart disease; however, these drugs may not be used by men who take nitroglycerine or related drugs. Further, they can drop the blood pressure. It’s usually not enough to cause problems, but your heart doctor can tell you whether it is safe for you.

Testosterone is used only in men with signs and symptoms of low testosterone and at least two documented low blood levels, ideally with tests taken at 8 a.m.

DEAR DR. ROACH: What’s the difference between smoking tobacco, marijuana or clove to our body? They all are from plants. Why are some OK or legal and the others are not? — I.F.

ANSWER: Just because a substance is a plant or plant-derived does not mean it is safe.

Tobacco contains nicotine, a habit-forming and moderately toxic chemical. Cigarette smoke is dangerous. It causes dramatic increase in the risk of heart disease and cancer, and smoking kills approximately 500,000 people per year in the U.S. alone, 7 million worldwide. It is legal.

Cannabis contains, among other substances, the psychoactive chemical THC, which causes a euphoria (“high”) in most people. This can cause poor judgment, especially at higher doses, and it increases driving risk. There is good evidence that cannabis, when used by teenagers, causes an increased risk for schizophrenia.

However, the number of deaths due to cannabis is very low. Proponents say it’s zero, but there are certainly case reports of deaths linked to cannabis use. But that number is extremely small compared with tobacco.

Clove cigarettes are usually made with tobacco as well, so they have the same risk as regular tobacco cigarettes.

Smoking any substance can cause damage to the lungs, potentially leading to chronic lung disease. These are less likely in cannabis smokers, as they tend to smoke much less than tobacco smokers. Cannabis extracts may also be ingested, rather than smoked, negating that risk.

Many states are in the process of legalizing cannabis for medical and recreational use. In the U.S., federal law continues to view cannabis and its extracts as illegal substances, although the U.S. government has generally not been enforcing the law in recent years.

If the law is intended to reduce harm, then the current legal situation is not logical.

* * *

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.