The obvious answer would be to avoid taking drugs while preparing for a drug test. However, there are some substances or activities that can seem harmless as they are not related to drug use in any way but can throw off your test results and product a positive result. Doing your best to avoid these things will help to ensure your test goes as smoothly as possible. Secondhand smoke from marijuana should be avoided as inhaling it can increase the chances of the test picking up THC in your system. Some products can also trigger a false positive result, including hemp and poppy seeds, diet pills and cold remedies. These should all be avoided the morning of your drug test. Let the testing provider know if you are taking any supplements, over-the-counter medications or prescription medications as these can potentially interfere with your test results.