Severe. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Nalidixic acid may make the effects of your cancer medicine on your gastrointestinal tract more severe.
What might happen:
You may develop a bleeding ulcer or your intestines may be severely damaged.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know right away that you are taking these medicines together. Let your doctor know if you have any stomach or abdominal pain, vomit blood, have blood in your stools, or have black, tarry stools.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.NegGram (nalidixic acid) US prescribing information. Sanofi-Synthelabo, Inc. November, 2012.
2.Alkeran (melphalan hydrochloride) US prescribing information. Celgene Corporation October, 2005.