Brief answer...it is variable from few weeks to many months and sometimes can cause liver failure.
Detailed answer..
Hello,
Thanks for the query.
MACROBID ( Nitrofurantoin )  is an oral antibiotic and one  of the most common causes of drug induced liver disease and can cause either an acute or a chronic hepatitis-like syndrome that can be severe and lead to liver failure or cirrhosis.
The acute liver injury usually subsides rapidly in few weeks once the drug is withdrawn but sometimes it can cause acute liver failure.
The chronic form of liver toxicity is much more common than acute liver toxicity and typically occurs after a prolonged longterm therapy.
Severity of nitrofurantoin induced injury ranges from just simple elevation of liver enzymes to fulminant liver failure failure and death.
Generally complete recovery takes place after stopping the drug but the recovery may be slow in some cases and may take 3 to 6 months.
In rare cases the evidence of chronic liver injury persists.
I hope it helps however you may revert to me for any further query.
Best of luck
Thanks

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