Niacin - Cytoxan (Cyclophosphamide) Interaction
Herbal: Niacin
Also Known As: 3-Pyridinecarboxylic Acid, Vitamin B3
Drug: Cyclophosphamide
Brand names:
Cytoxan, Neosar
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
May 25, 2025
Interaction Details
Cyclophosphamide is classified as belonging to the following category: Hepatotoxic Drugs
Theoretically, concomitant use of niacin and hepatotoxic drugs might increase the risk of hepatotoxicity.
Niacin has been associated with cases of liver toxicity, especially when used in pharmacologic doses. Sustained-release niacin preparations appear to be associated with a higher risk of hepatotoxicity than immediate-release niacin.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- American Society of Health-System Pharmacists. ASHP Therapeutic Position Statement on the safe use of niacin in the management of dyslipidemias. Am J Health Syst Pharm 1997;54:2815-9.
- Bays HE, Dujovne CA. Drug interactions of lipid-altering drugs. Drug Saf 1998;19:355-71.
- Rader JI, Calvert RJ, Hathcock JN. Hepatic toxicity of unmodified and time-release preparations of niacin. Am J Med 1992;92:77-81.
- Etchason JA, Miller TD, Squires RW, et al. Niacin-induced hepatitis: a potential side effect with low-dose time-release niacin. Mayo Clin Proc. 1991;66(1):23-8.
- Henkin Y, Johnson KC, Segrest JP. Rechallenge with crystalline niacin after drug-induced hepatitis from sustained-release niacin. JAMA. 1990;264(2):241-3.
- Henkin Y, Oberman A, Hurst DC, Segrest JP. Niacin revisited: clinical observations on an important but underutilized drug. Am J Med. 1991;91(3):239-46.
- Bassan M. A case for immediate-release niacin. Heart Lung. 2012 Jan-Feb;41(1):95-8.
- Nawaz N, Mistretta T, Karime C, Lewis J, Wolf E. Cholestatic Drug-Induced Liver Injury in a Patient Taking High-Dose Niacin for Hyperlipidemia. J Investig Med High Impact Case Rep 2024;12:23247096231224349.
Niacin Overview
Niacin, also known as vitamin B3, is a water-soluble vitamin found in a variety of foods, including meat, poultry, fish, and fortified grains.
It plays a variety of roles in the body, including in the metabolism of carbohydrates, fats, and proteins. It is also necessary for the production of energy in the body and in the synthesis of different hormones.
Niacin deficiency is rare in developed countries, however, supplementation has been shown to have several positive benefits. For example, it can reduce the risk of diabetic neuropathy (i.e., nerve pain) and has been shown effective for treating some types of high cholesterol (extended-release niacin is used as a prescription drug in the United States for this purpose).
There is a multitude of niacin forms available as dietary supplements, including NADH, niacinamide, and nicotinamide riboside, all with different properties.
Cyclophosphamide Overview
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Cyclophosphamide is used alone or in combination with other medications to treat Hodgkin's lymphoma (Hodgkin's disease) and non-Hodgkin's lymphoma (types of cancer that begin in a type of white blood cells that normally fights infection); cutaneous T-cell lymphoma (CTCL, a group of cancers of the immune system that first appear as skin rashes); multiple myeloma (a type of cancer of the bone marrow); and certain types of leukemia (cancer of the white blood cells), including chronic lymphocytic leukemia (CLL), chronic myelogenous leukemia (CML), acute myeloid leukemia (AML, ANLL), and acute lymphoblastic leukemia (ALL). It is also used to treat retinoblastoma (cancer in the eye), neuroblastoma (a cancer that begins in nerve cells and occurs mainly in children), ovarian cancer (cancer that begins in the female reproductive organs where eggs are formed), and breast cancer. Cyclophosphamide is also used to treat nephrotic syndrome (a disease that is caused by damage to the kidneys) in children whose disease has not improved, has gotten worse, or has come back after taking other medications or in children who experienced intolerable side effects with other medications. Cyclophosphamide is in a class of medications called alkylating agents. When cyclophosphamide is used to treat cancer, it works by slowing or stopping the growth of cancer cells in your body. When cyclophosphamide is used to treat nephrotic syndrome, it works by suppressing your body's immune system.
Niacin - More Interactions
Niacin interacts with 698 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
| Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
| Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
| Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
| Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.
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