Serious. These medicines may interact and cause very harmful effects. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Penicillin antibiotics may decrease the ability of your kidneys to remove methotrexate from your body.
What might happen:
The levels of methotrexate in your body may increase and cause serious. possibly life-threatening, side effects.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. Your doctor may want to monitor the amount of methotrexate in your blood, change the dose of your methotrexate, or change your antibiotic. Let your doctor know right away if you develop nausea, stomach pain, yellowing of the eyes or skin, dark urine, fever, fatigue, a persistent sore throat, easy bruising or bleeding, black stools, a change in the amount of urine you pass, skin rash, breathing problems, dry cough, diarrhea, or mouth sores while taking these medicines together or after finishing taking these medicine together.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.
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