Multiple myeloma is not contagious. It cannot be spread from one person to another through physical contact, kissing, sharing food, sexual activity, or any other form of close interaction. Under no circumstances can you “catch” multiple myeloma from someone who has it.
Why Myeloma Cannot Spread Between People
Multiple myeloma is a cancer of plasma cells, a type of white blood cell that normally produces antibodies to fight infection. In myeloma, these plasma cells develop genetic mutations that cause them to multiply uncontrollably inside the bone marrow. The abnormal cells crowd out healthy blood cells and can form tumors in multiple bones throughout the body.
This process starts entirely within one person’s own body. Unlike infections caused by bacteria, viruses, or parasites, cancer cells are the person’s own cells that have gone wrong. They aren’t foreign organisms that can travel from one host to another. Even if myeloma cells were somehow transferred to another person, that person’s immune system would recognize them as foreign tissue and destroy them, the same way a body rejects an incompatible organ transplant.
Why Some People Wonder About Contagion
People with multiple myeloma are significantly more vulnerable to infections. Because myeloma cells take over the bone marrow, they crowd out the normal white blood cells and healthy plasma cells that the immune system relies on. This means myeloma patients often get sick more frequently and more severely than healthy people. If you live with or care for someone with myeloma and they seem to be constantly battling infections, it’s natural to wonder whether the cancer itself could be transmitted. It can’t. The infections are a consequence of the weakened immune system, not evidence that the cancer spreads.
Family Risk Is Genetic, Not Infectious
Another reason people may question whether myeloma is contagious is that it sometimes appears to run in families. First-degree relatives of someone with myeloma have a two- to fourfold higher risk of developing the disease or its precursor conditions. But this clustering is genetic, not infectious. Certain inherited variations in DNA repair genes can make a person more susceptible to the kind of mutations that lead to myeloma. Living in the same house doesn’t increase your risk. Sharing DNA does.
That said, even with a family history, myeloma remains uncommon. An estimated 36,000 new cases are expected in the United States in 2026, and the median age at diagnosis is 69. Most people with a family connection to myeloma will never develop it themselves.
How Myeloma Actually Develops
Myeloma doesn’t appear overnight. It almost always begins with a precursor condition called monoclonal gammopathy of undetermined significance, or MGUS. In MGUS, a small number of abnormal plasma cells are present in the bone marrow, but they aren’t causing symptoms or damage. About 1% of people with MGUS progress to multiple myeloma each year, according to data from the National Cancer Institute. Many people live with MGUS for decades and never develop cancer.
What triggers the progression from MGUS to active myeloma isn’t fully understood, but the known risk factors are all internal or environmental rather than infectious. Older age, male sex, Black race, obesity, and exposure to certain chemicals like pesticides or herbicides are associated with higher risk. None of these involve person-to-person transmission.
Living With or Caring for Someone With Myeloma
If someone in your life has been diagnosed with multiple myeloma, you do not need to take any precautions to protect yourself from the cancer. You can share meals, hug, sleep in the same bed, and provide hands-on care without any risk of developing myeloma yourself.
The precautions that do matter go in the other direction. Because myeloma weakens the immune system, your loved one is more vulnerable to the colds, flu, and other infections that you might carry. Washing your hands, staying current on your own vaccinations, and avoiding close contact when you’re sick are all practical ways to protect them. The concern is never that they’ll give you cancer. It’s that everyday germs could make them seriously ill.