Do I need drugs if Ive has a BCG?

I had a skin test for TB which came out positive. My MD says I need to take six months of medication which may cause liver damage and other side effects. I am from the UK so I've had a BCG - won't I always have a poisitive skin test?? Do I really need to take the medication??
Thanks.

[National Jewish]

Most people who had Bacille Calmette-Guerin (BCG) vaccine as a child do not react positively to PPD as an adult.  Therefore, when we see an adult with a positive PPD we infer that he/she may have been infected with TB (especially if they are at risk as a health care worker or other exposures).  Since we don't believe that a childhood BCG protects against adult TB, we too recommend Isoniazid (INH) preventive therapy.