Suggest The Decongestant That Does Not Contain Methamphetamine

Hello, My son is living in a sober house for drug addictions. He is doing very well in his recovery. He has many allergies and has been on Zyrtec and sudafed for many years. Now that he is drug tested, it caused a false positive for methamphetamine. He doesnt have insurance at the moment, and it cost 600 to prove that it was a false positive. Is there any allergy medicine or decongestant he can take that wont cause a false positive on a urine test. Thanks in advance for your help