Fluorouracil

Also indexed as: 5-FU, Adrucil®, Efudex®, Fluoroplex®

Fluorouracil is a chemotherapy drug given intravenously (iv) to treat colon, rectum, breast, stomach, and pancreas cancers. Fluorouracil is also available in creams and solutions for topical treatment of some skin cancers and genital warts.

Note: Many of the interactions described below, in the text and in the Summary of Interactions, have been reported only for specific chemotherapeutic drugs, and may not apply to other chemotherapeutic drugs. There are many unknowns concerning interactions of nutrients, herbs, and chemotherapy drugs. People receiving chemotherapy who wish to supplement with vitamins, minerals, herbs, or other natural substances should always consult a physician.

Safetychecker Summary for Fluorouracil
(for details about the summarized interactions, read the full article)

Beneficial May be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them.

Taurine*

Multiple nutrients* (malabsorption)
Beneficial May be Beneficial: Side effect reduction/prevention—Taking these supplements may help reduce the likelihood and/or severity of a potential side effect caused by the medication.

Beta-carotene* (mouth sores)

Spleen peptide extract* (see text)

Eleuthero* (see text)

Ginger* (nausea)

Chamomile* (mouth sores)

Glutamine* (mouth sores)

Glutamine (intestinal toxicity)

Melatonin

Vitamin B6

N-acetyl cysteine* (NAC)

Thymus peptides* (see text)

Vitamin E*, topical (mouth sores)
Beneficial May be Beneficial: Supportive interaction—Taking these supplements may support or otherwise help your medication work better.

Antioxidants*

Melatonin

Milk thistle*

PSK*
Check Check: Other—Before taking any of these supplements or eating any of these foods with your medication, read this article in full for details.

Echinacea*

Multivitamin-mineral*

Vitamin A*

Vitamin C*
Reduced drug absorption/bioavailability

None known
Adverse interaction

None known

An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.

Interactions with Dietary Supplements

Antioxidants
Chemotherapy can injure cancer cells by creating oxidative damage. As a result, some oncologists recommend that patients avoid supplementing antioxidants if they are undergoing chemotherapy. Limited test tube research occasionally does support the idea that an antioxidant can interfere with oxidative damage to cancer cells.1 However, most scientific research does not support this supposition.

A modified form of vitamin A has been reported to work synergistically with chemotherapy in test tube research.2 Vitamin C appears to increase the effectiveness of chemotherapy in animals3 and with human breast cancer cells in test tube research.4 In a double-blind study, Japanese researchers found that the combination of vitamin E, vitamin C, and N-acetyl cysteine (NAC)—all antioxidants—protected against chemotherapy-induced heart damage without interfering with the action of the chemotherapy.5

A comprehensive review of antioxidants and chemotherapy leaves open the question of whether supplemental antioxidants definitely help people with chemotherapy side effects, but the article strongly suggests that antioxidants need not be avoided for fear that the actions of chemotherapy would be interfered with.6

A new formulation of selenium (Seleno-Kappacarrageenan) was found to reduce kidney damage and white blood cell–lowering effects of cisplatin in one human study. However, the level used in this study (4,000 mcg per day) is potentially toxic and should only be used under the supervision of a doctor.7

Glutathione, the main antioxidant found within cells, is frequently depleted in individuals on chemotherapy and/or radiation. Preliminary studies have found that intravenously injected glutathione may decrease some of the adverse effects of chemotherapy and radiation, such as diarrhea.8

Glutamine
Though cancer cells use glutamine as a fuel source, studies in humans have not found that glutamine stimulates growth of cancers in people taking chemotherapy.9 10 In fact, animal studies show that glutamine may actually decrease tumor growth while increasing susceptibility of cancer cells to radiation and chemotherapy,11 12 though such effects have not yet been studied in humans.

Glutamine has successfully reduced chemotherapy-induced mouth sores. In one trial, people were given 4 grams of glutamine in an oral rinse, which was swished around the mouth and then swallowed twice per day.13 Thirteen of fourteen people in the study had fewer days with mouth sores as a result. These excellent results have been duplicated in some,14 but not all15 double-blind research. In another study, patients receiving high-dose paclitaxel and melphalan had significantly fewer episodes of oral ulcers and bleeding when they took 6 grams of glutamine four times daily along with the chemotherapy.16

One double-blind trial suggested that 6 grams of glutamine taken three times per day can decrease diarrhea caused by chemotherapy.17 However, other studies using higher amounts or intravenous glutamine have not reported this effect.18 19

Intravenous use of glutamine in people undergoing bone marrow transplants, a procedure sometimes used to allow very high amounts of chemotherapy to be used, has led to reduced hospital stays, leading to a savings of over $21,000 for each patient given glutamine.20

In a double-blind study, supplementation with 18 grams of glutamine per day for 15 days, starting five days before the beginning of 5-FU therapy, significantly reduced the severity of drug-induced intestinal toxicity.21

Intravenous use of glutamine in people undergoing bone marrow transplants, a procedure sometimes used to allow very high amounts of chemotherapy to be used, has led to reduced hospital stays, leading to a savings of over $21,000 for each patient given glutamine.22

Melatonin
Melatonin supplementation (20 mg per day) has decreased toxicity and improved effectiveness of chemotherapy with 5-FU plus folinic acid and 5-FU plus cisplatin.23

N-acetyl cysteine (NAC)
NAC, an amino acid–like supplement that possesses antioxidant activity, has been used in four human studies to decrease the kidney and bladder toxicity of the chemotherapy drug ifosfamide.24 25 26 27 These studies used 1–2 grams NAC four times per day. There was no sign that NAC interfered with the efficacy of ifosfamide in any of these studies. Intakes of NAC over 4 grams per day may cause nausea and vomiting.

The newer anti-nausea drugs prescribed for people taking chemotherapy lead to greatly reduced nausea and vomiting for most people. Nonetheless, these drugs often do not totally eliminate all nausea. Natural substances used to reduce nausea should not be used instead of prescription anti-nausea drugs. Rather, under the guidance of a doctor, they should be added to those drugs if needed. At least one trial suggests that NAC, at 1,800 mg per day, may reduce nausea and vomiting caused by chemotherapy.28

Spleen Extract
Patients with inoperable head and neck cancer were treated with a spleen peptide preparation (Polyerga®) in a double-blind trial during chemotherapy with cisplatin and 5-FU.29 The spleen preparation had a significant stabilizing effect on certain white blood cells. People taking it also experienced stabilized body weight and a reduction in the fatigue and inertia that usually accompany this combination of chemotherapy agents.

Beta-carotene and Vitamin E
Chemotherapy frequently causes mouth sores. In one trial, people were given approximately 400,000 IU of beta-carotene per day for three weeks and then 125,000 IU per day for an additional four weeks.30 Those taking beta-carotene still suffered mouth sores, but the mouth sores developed later and tended to be less severe than mouth sores that formed in people receiving the same chemotherapy without beta-carotene.

In a study of chemotherapy-induced mouth sores, six of nine patients who applied vitamin E directly to their mouth sores had complete resolution of the sores compared with one of nine patients who applied placebo.31 Others have confirmed the potential for vitamin E to help people with chemotherapy-induced mouth sores.32 Applying vitamin E only once per day was helpful to only some groups of patients in another trial,33 and not all studies have found vitamin E to be effective.34 Until more is known, if vitamin E is used in an attempt to reduce chemotherapy-induced mouth sores, it should be applied topically twice per day and should probably be in the tocopherol (versus tocopheryl) form.

Vitamin A
A controlled French trial reported that when postmenopausal late-stage breast cancer patients were given very large amounts of vitamin A (350,000–500,000 IU per day) along with chemotherapy, remission rates were significantly better than when the chemotherapy was not accompanied by vitamin A.35 Similar results were not found in premenopausal women. The large amounts of vitamin A used in the study are toxic and require clinical supervision.

Multivitamin-mineral
Many chemotherapy drugs can cause diarrhea, lack of appetite, vomiting, and damage to the gastrointestinal tract. Recent anti-nausea prescription medications are often effective. Nonetheless, nutritional deficiencies still occur.36 It makes sense for people undergoing chemotherapy to take a high-potency multivitamin-mineral to protect against deficiencies.

Taurine
Taurine has been shown to be depleted in people taking chemotherapy.37 It remains unclear how important this effect is or if people taking chemotherapy should take taurine supplements.

Thymus peptides
Peptides or short proteins derived from the thymus gland, an important immune organ, have been used in conjunction with chemotherapy drugs for people with cancer. One study using thymosin fraction V in combination with chemotherapy, compared with chemotherapy alone, found significantly longer survival times in the thymosin fraction V group.38 A related substance, thymostimulin, decreased some side effects of chemotherapy and increased survival time compared with chemotherapy alone.39 A third product, thymic extract TP1, was shown to improve immune function in people treated with chemotherapy compared with effects of chemotherapy alone.40 Thymic peptides need to be administered by injection. People interested in their combined use with chemotherapy should consult a doctor.

Vitamin B6
Fluorouracil occasionally causes problems on the skin of the palms and soles. Preliminary reports have appeared showing that 100 mg per day of vitamin B6 can sometimes eliminate the pain associated with this drug-induced condition.41 42

Interactions with Herbs

Echinacea (Echinacea purpurea, Echinacea angustifolia)
Echinacea is a popular immune-boosting herb that has been investigated for use with chemotherapy. One study investigated the actions of cyclophosphamide, echinacea, and thymus gland extracts to treat advanced cancer patients. Although small and uncontrolled, this trial suggested that the combination modestly extended the life span of some patients with inoperable cancers.43 Signs of restoration of immune function were seen in these patients.

Eleuthero  (Eleutherococcus senticosus)
Russian research has looked at using eleuthero with chemotherapy. One study of patients with melanoma found that chemotherapy was less toxic when eleuthero was given simultaneously. Similarly, women with inoperable breast cancer given eleuthero were reported to tolerate more chemotherapy.44 Eleuthero treatment was also associated with improved immune function in women with breast cancer treated with chemotherapy and radiation.45

Milk thistle  (Silybum marianum)
Milk thistle’s major flavonoids, known collectively as silymarin, have shown synergistic actions with the chemotherapy drugs cisplatin and doxorubicin (Adriamycin®) in test tubes.46 Silymarin also offsets the kidney toxicity of cisplatin in animals.47 Silymarin has not yet been studied in humans treated with cisplatin. There is some evidence that silymarin may not interfere with some chemotherapy in humans with cancer.48

Ginger (Zingiber officinale)
Ginger can be helpful in alleviating nausea and vomiting caused by chemotherapy.49 50 Ginger powder in tablets or capsules can be taken for nausea, in 500 mg amounts every two or three hours, for a total of 1 gram per day.

German chamomile (Matricaria recutita)
A liquid preparation of German chamomile has been shown to reduce the incidence of mouth sores in people receiving radiation and systemic chemotherapy treatment in an uncontrolled study. 51

PSK (Coriolus versicolor)
The mushroom Coriolus versicolor contains an immune-stimulating substance called polysaccharide krestin, or PSK. PSK has been shown in several studies to help cancer patients undergoing chemotherapy. One study involved women with estrogen receptor-negative breast cancer. PSK combined with chemotherapy significantly prolonged survival time compared with chemotherapy alone.52 Another study followed women with breast cancer who were given chemotherapy with or without PSK. The PSK-plus-chemotherapy group had a 25% better chance of survival after ten years compared with those taking chemotherapy without PSK.53 Another study investigated people who had surgically removed colon cancer. They were given chemotherapy with or without PSK. Those given PSK had a longer disease-free period and longer survival time.54 Three grams of PSK were taken orally each day in these studies.

Although PSK is rarely available in the United States, hot-water extract products made from Coriolus versicolor mushrooms are available. These products may have activity related to that of PSK, but their use with chemotherapy has not been studied.

Interactions with Foods and Other Compounds

Fruit drinks
Often, people who undergo chemotherapy develop aversions to certain foods, sometimes making it permanently difficult to eat those foods. Exposing people to what researchers have called a “scapegoat stimulus” just before the administration of chemotherapy can direct the food aversion to the “scapegoat” food instead of more important parts of the diet. In one trial, fruit drinks administered just before chemotherapy were most effective in protecting against aversions to other foods.55

References:

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