The redness and enlargement of flat warts after using Vicodin may be due to an adverse reaction to the medication, if there is no significant pain, you can continue to use it, which is a common irritant effect of the drug. However, if it has pain or skin breakage, etc., the drug should be discontinued. Retinoic acid cream is mainly used for the treatment of acne vulgaris or keratosis pilaris. The retinoic acid ingredient may cause skin irritation such as burning, redness or flaking during application, but it also indicates that the drug ingredient is working significantly. Mild redness, swelling or enlargement of flat warts during application of retinoic acid ointment is a normal irritant effect of the medication and can be temporarily observed and the medication continued to be applied. However, if the warts are irritated by the drug and there is severe localized pain, skin breakage or severe skin loss, then you need to consider stopping the drug or changing the drug, and you should consult your doctor. Flat warts in the use of retinoic acid in the process of the occurrence of uncomfortable symptoms, should be used with caution under the guidance of a doctor or stop using.