How long does Rogaine take to flush out of the system?

Topical minoxidil has been said to have a half life of about 22 hours. The drug leaves the system to significant degrees within about a week.  However, if one is having an allergic reaction, the immune system can remain in a state of heightened alertness for a longer period of time - even many weeks to months. So the answer is not as simple as asking how long does minoxidil last in one's system.  Anyone who is have rash and swelling and blurred vision should consider seeking medical attention on a more urgent basis, especially if any one of the symptoms is worsening. 

According to the surgeons and the studies it takes 3-4 months approx. to see the results from Rogaine. The medication absorbs into the body as well as cause more skin irritation. Rogaine should be only used on the scalp and wash your hands after applying the medication.

Your skin should get back to normal in 7-8 days. By the experience in my practice we have concluded that the possibility of Allergy or intolerance appearing is pretty much tied to a Brand of the Minoxidil manufacturer.  If your allergy symptoms are high, you should take some antihistamine (first, of course, consult your doctor) in order to lower the effect of Allergy. 

Based on your description hat does sound like an allergic reaction, either to the Rogaine itself or to whatever it is mixed in.  It should resolve within a week or so.  Medications such as Benadryl and steroid cream can help, though if it is particularly bad (blurred vision is unusual unless it's due to your eyes watering) a visit to your primary physician or urgent care may be a good idea.

Minoixidil had a half life less than a day.  This means that every day or so, half of the remaining minoxidil is out of your system In two days 1/4 remains and so on