Some medications may cause cloudy urine as a side effect. For example, solifenacin, which can treat an overactive bladder, may cause cloudy urine. If this happens, a person should contact a doctor immediately, as it can be a serious side effect. In some cases, medications may increase the risk of conditions that can cause cloudy urine. Oxybutynin, an antispasmodic, can lead to a UTI, which in turn can cause cloudy urine.