Quite what the OP meant by his question on cold medicines has not been addressed
Cold medication often contain codeine which is metabolised into morphine. Sympathomimetics such as pseudoephedrine, ephedrine, and phenylephrine are used as decongestants. All of the above can result in a positive test if screened for drugs as well as alcohol. It is wise to keep a written note of any medication taken and tell the screener before the test is carried out.