Drugs you might use for a skin condition would be suppressive, and might slow the action of the homeopathic remedy, but nothing can interfere with it completely. You might want to consider that a skin symptom is usually a good thing, as the body is throwing the disturbance outward instead of inward, so it's best to avoid suppressing skin symptoms if possible.
Once probably wouldn't hurt, but over a period of time a suppressive treatment can drive the disturbance deeper into the body where you could develop a much worse condition that would be harder to treat. So use the suppressive drugs cautiously.
Hope that helps.