Cancer patients should be told by their doctors if they are taking herbal products because some of the ingredients may stop their treatment, a cancer conference heard.
Garlic, ginger and ginkgo tablets, for example, can delay the healing of skin lesions when breast cancer is spread.
Surgeon Prof Maria Joao Cardoso, said there was no evidence that herbal therapies or creams were working.
When in doubt, it's best not to take anything, he said.
"" Doctors need to be more active about asking their patients what they should take when they are treated for cancer, "said Prof Cardoso, head breast surgeon at the Champalimaud Cancer Center in Lisbon, Portugal, told the BBC.
He said it was particularly important that patients should always check with their doctors before trying out complementary therapies for skin cancer.
This occurs in one in five cases of breast cancer ̵1; and less than other cancers.  Copyright copyright
The danger is that many products may interfere with hormone therapies or chemotherapy treatments, and the some new ones slow down the blood clotting process – which can lead to wounds lasting longer to heal and sticking together.] He has shown the following herbal products as example of those who slow down the flowering:
& # 39; Don't get along & # 39;
Prof Cardoso says it is not surprising that patients and their caregivers look for complementary or alternative treatments that may make a difference.
But he said that people should know that "they can end up doing more harm than good".
"The highest goal in medicine is important to remember: don't get along," he said.
On its website, Cancer Research UK states that some complementary treatments may stop conventional treatments working as well as them.
It is also said that it is important to avoid certain foods and beverages such as pomegranates and oranges in cancer treatment, as they may affect how well the cancer drugs are damaged in the body.
The charity says: "Talk to your doctor about any auxiliary therapies you plan to use. Tell them before you start getting assisted therapy, especially if you are in the middle of a course of treatment on cancer. "
Grete Brauten-Smith, charity charity clinical nurse Breast Cancer Today says:" With the amount of unpublished information available online and little reliable research on these products, a discussion on a healthcare professional can ensure that a patient has the accurate information they need to make a informed choice. "
Speaking at the Advanced Breast Cancer Fifth International Consensus Conference, Prof Cardoso said that therapies such as yoga, mindfulness, reiki and acupuncture can have a positive impact on patients' quality of life.