The answer is yes. DUI in Florida includes alcohol and any controlled substance. This could even include prescription medications, such as Xanax and Ambien.
The bottom line is that it is illegal to drive impaired. Whether impaired by alcohol or by drugs, it does not matter in the eyes of the law.
However, breath tests are designed to test only for alcohol. The only way to test for drugs is a urine test or blood test. And in many cases where a driver is suspected of being under the influence of drugs and not alcohol, a DRE, or Drug Recognition Expert, will come in and conduct a physical and visual examination of the accused. The DRE may then opine that the accused is under the influence of a specific drug.
You may refuse a urine test, and the same rules apply as refusing a breath test. Your license will be suspended for refusing a urine test. One year for your first refusal, and eighteen months for your second refusal.
However, if you elect to take a breath test a blow all zeros, and then refuse to submit to a urine test - your license will be suspended. If you blow all zeros or under a .08 and then submit to a urine test, your license will NOT be suspended by the Florida DHSMV, even if the urine test later shows that you had illegal drugs in your system.
The Court, however, can suspended your license as result of a plea or conviction at trial (a DHSMS or administrative suspension is not the same as a Court suspension).
If you blow all zeros (or close to it), talk to a DUI attorney about possible defenses that could lead to dismissal or a reduction to reckless driving.