DEAR DR. ROACH: I read that condoms have tiny holes in them, and that they don’t provide protection against HIV/AIDS. Is this true? — G.D.M.

ANSWER: Condoms do have tiny holes in them if magnified enough; however, latex condoms are effective at preventing HIV transmission, both measured in a laboratory as well as in clinical studies. In couples who use condoms 100 percent of the time, HIV transmission is reduced by at least 90 to 95 percent.

Another way of reducing transmission is by pre-exposure prophylaxis. This involves taking a medication in order to prevent infection. In people who took the medication as directed, there was a 96 percent reduction in HIV transmission. The combination of pre-exposure prophylaxis and condoms provides an even greater reduction in risk. Condoms also provide protection against other possible sexually transmitted infections.

Post-exposure prophylaxis is appropriate for someone who had condomless sexual intercourse with a person potentially infected with HIV or who had a needlestick from a person known or suspected to have HIV.

Another way of reducing HIV transmission is to treat the person who is infected. With effective treatment, most people with HIV can achieve no detectable virus in the blood. With no detectable virus in the blood, the risk for infection becomes very, very low, with more than 99 percent effectiveness at preventing transmission. This is partly why it’s so important to identify and treat everyone with HIV as early as possible. The Centers for Disease Control and Prevention recommends routine testing for everyone, and I agree.

Finally, people can reduce HIV transmission by abstinence — that is, not having sex and not sharing needles or other devices that can transmit blood.

DEAR DR. ROACH: I’m an 83-year-old widower. I had a quadruple bypass 15 years ago, but I exercise regularly and I think my health is good. I have been using a homeopathic human growth hormone supplement gel for the skin. It costs $170 for a six-week supply. Is this good for my health, or can it hurt me? — C.F.

ANSWER: I looked at the information about the supplement, and I don’t think it is good for your health. However, it isn’t likely to harm you except financially.

The supplement contains human growth hormone. Human growth hormone does have important actions in the body, and when used in pharmacologic doses in adults, it increases muscle growth. It’s used by people with muscle wasting caused by HIV, for example. Athletes have used this drug illicitly to improve athletic performance, although it has not been proven to improve strength, power or endurance.

HGH is not absorbed when taken orally, and although there has been some research on skin absorption of HGH after treating the skin with radiofrequency energy to create channels for the drug to be absorbed, it still is not well-absorbed through intact, healthy skin.

Further, the information I found shows that the HGH in your supplement is present at a “30X” dilution. This doesn’t mean it is diluted to one part in 30: “30X” in homeopathic products means that it has been diluted a billion, billion, trillion times, and that there is virtually no chance that there is even a single molecule of HGH in a year’s worth of gel, which likely wouldn’t be absorbed anyway. My advice is to save your money.

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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.

Dr. Roach