A positive drug test can be wrong

False suspicions can arise if the person tested has previously taken medication. Tests can be falsified by more than 30 different drugs, including widely used drugs such as cough syrups, antibiotics, and the pain reliever ibuprofen. Even a large meal can cause false positive drug tests. A strong poppy seed cut may trigger an opiate alarm. The specialist literature knows case reports according to which people were wrongly mistaken for drug users after drinking a few glasses of quinine-containing tonic water.

In contrast, lovers of hemp tea seem to be on the safe side. Traces of cannabis in the urine usually remain below the limit values ‚Äč‚Äčthat speak for drug use. The same applies to passive cannabis smoking. Even after three hours in the Dutch coffee shop, test subjects had not reached any critical urine values.

What does this mean for the common man? Does anyone who has to eat grandmother's poppy seed cake or fight their headache with a pill, expect to be mistaken for a junkie in a drug control?

The average German is most likely to get embarrassed at a traffic control of having to give a urine sample. "Almost every patrol vehicle also has rapid drug tests on board," says the Berlin police chief inspector Stefan Drescher. The police order 20,000 such one-time tests per year for the urban area. Who is asked to pass urine in the nearest toilet, in an emergency also in the ditch, is at the discretion of the police. "Usually the drivers tested are those who stand out due to driving uncertainty or show abnormalities typical of drugs, such as red conjunctiva on the eye, dilated pupils or lack of concentration."

If the quick test is positive, the driver does not yet have any legal consequences, but has to fear inconvenience. In many cases, he is taken to the police station to take a blood sample. Then he can go home - but without a car. The blood sample is meanwhile examined with the reliable gas chromatograph. Only if the result is positive are there any legal consequences.

Drug detection is sometimes handled more laxly in the clinical area. Drug tests are used, for example, to confirm a suspected poisoning or to monitor therapies of drug addicts. There is not enough time or money to verify a rapid test result in all situations. "In the worst case, this can mean that patients are wrongly excluded from drug withdrawal therapy or receive incorrect or unnecessary treatment because of alleged evidence of poisoning," says Hans Maurer, head of the department for clinical toxicology at Saarland University.