PS -- I neglected to say that Macrodantin is the brand name of generic nitrofurantoin, which is the name used in the information above.
The US National Institutes of Health (NIH), which are run by the US government, and so aren't part of any pharmaceutical company, has a website that says the following, among other things -- the last item listed under 'call your doc if ...' is if you get a skin rash:
Nitrofurantoin(nye troe fyoor an' toyn)
Last Revision: November 1, 2010. ... Nitrofurantoin may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
* dark yellow or brown urine
* nausea
* vomiting
* loss of appetite
Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:
* difficulty breathing
* excessive tiredness
* fever or chills
* chest pain
* persistent cough
* numbness, tingling, or pinprick sensation in the fingers and toes
* muscle weakness
* swelling of the lips or tongue
* skin rash <<<<<<=======
I'd call the doc. It might not be a problem, but better to check it out.