As an ul­tra­fil­tra­te of the blood, sa­li­va or oral flu­id could pre­sent as a sui­ta­ble me­di­um to ve­ri­fy the pre­sence of drugs of abu­se. And not on­ly that: in con­trast to uri­ne, sa­li­va could al­so pro­vi­de in­for­ma­ti­on re­gar­ding the le­vel of cur­rent in­to­xi­ca­ti­on, which would be of gre­at si­gni­fi­can­ce for roadsi­de tes­ting. No one would have to uri­na­te in­to a cup or ex­po­se their ge­ni­tals.

Howe­ver, the­re is a who­le se­ri­es of pro­blems and un­ans­we­red ques­ti­ons with re­gard to sa­li­va, which must be ta­ken in­to con­side­ra­ti­on:

  • It must be as­su­med that the sa­li­va is sub­ject to si­gni­fi­cant va­ria­ti­ons from one sub­ject to ano­ther. Sa­li­va se­cre­ti­on is a com­plex pro­cess, and ana­to­mic­al/his­to­lo­gi­cal con­di­ti­ons play an im­por­tant ro­le. Even fac­tors such as stress, hun­ger or un­der­ly­ing sys­te­mic di­sea­ses may have an in­flu­ence on the com­po­si­ti­on and con­sis­ten­cy of sa­li­va. As a re­sult, stan­dar­dis­ati­on of the me­thod is prac­ti­cal­ly im­pos­si­ble.
  • Dif­fe­rent sub­s­tan­ces re­ach the oral flu­id through dif­fe­rent ways and in dif­fe­rent forms. For ex­ample, can­na­bi­no­ids can be de­tec­ted on­ly for 30 mi­nu­tes af­ter one­time use. The de­tec­tion time for ocai­ne and its me­ta­boli­tes is si­gni­fi­cant­ly lon­ger. Howe­ver, their de­tec­tion time is dra­ma­ti­cal­ly af­fec­ted by che­wing gum or le­mon drops (Hal­wachs 2011). At the least, the lat­ter cle­ar­ly chal­len­ges the theo­ry that sa­li­va can­not be ma­ni­pu­la­ted. Howe­ver, fur­ther in­ves­ti­ga­ti­on is cer­tain­ly re­qui­red.
  • The vo­lu­me of sa­li­va collec­ted in any one sam­ple is ve­ry small. The­re­fo­re, sa­li­va pro­duc­tion is si­mu­la­ted – of­ten by the sa­li­va collec­tion sys­tems them­sel­ve by using aci­dic me­dia. This in­flu­en­ces the pH-va­lue of the sam­ple and thus in­flu­en­ces the sub­s­tan­ces se­ar­ched and their de­tec­tion times. In ad­di­ti­on, sta­bi­li­zers are used for trans­por­ting the sam­ple. The­se as well can in­flu­ence the ana­ly­sis. Ne­verthe­less, fur­ther re­se­arch in this re­gard is ur­gent­ly re­qui­red.
  • The si­mu­la­ti­on of sa­li­va­ry flow its­elf re­pres­ents in in­ter­ven­ti­on in bo­di­ly func­tions, ma­king such pro­ce­du­res im­per­mis­si­ble for ex­ample in pe­nal in­sti­tu­ti­ons. For mo­re in­for­ma­ti­on plea­se re­fer to our sec­tion In Pe­nal Sys­tem/Pro­ba­ti­on Ser­vices.
  • The low sam­ple vo­lu­me re­qui­res high­ly sen­si­ti­ve and ex­pen­si­ve ana­ly­ti­cal me­thods. The­re are quick tests availa­ble in the mar­ket. But ma­jor in­ter­na­tio­nal stu­dies such as RO­SI­TA or DRUID do not re­com­mend the­se tests due to high pro­ba­bi­li­ty of er­rors and lack of stan­dards with re­gard to th­res­hold va­lu­es.


It can be sum­ma­ri­sed that the sa­li­va as a me­di­um has a hu­ge po­ten­ti­al, but it has not be­en re­se­ar­ched ade­qua­te­ly to use it in cli­ni­cal prac­ti­ce. You can find mo­re in­for­ma­ti­on about this to­pic in our Down­load Cent­re.

Capillary blood

Any mixture of tissue fluid and blood is defined as capillary blood, which is collected by piercing fingertips or ear lobes. 
Blood as a medium has been researched adequately. However, capillary blood is not pure blood, which results in certain problems:


  • Differences in the analysis of capillary blood and venous serum or whole blood are well documented. Thus, blood sugar measurement from capillary blood is no longer permitted for diagnostics, therapy and post-operative care of gestational diabetes since 2011. Even deviations in the blood gas analysis were established in many studies. Therefore, capillary blood is not recommended.
  • Capillary blood contains a natural trace of tissue fluids. In order to minimise this, the first few drops should be rejected. However, it is hardly possible to quantify the proportion of tissue fluids.
  • This problem is exacerbated by the stimulation of insertion point. This can be done only with suitable hyperemising ointment or heating, because mechanical simulation like massage or pressing will further change the composition of the collected sample.
  • In addition, there is the risk of contamination, because taking samples with capillary tube is not a closed system. The research regarding possible contamination – e.g. due to hyperemising ointments – and its influence on tested substances is surprisingly sparse.
  • The extremely low quantity of sample drastically limits the reproducibility of the analysis. As a result, it significantly increases the probability of errors.
  • It should be noted that even this method of collecting capillary blood represents bodily intervention. Thus, the same legal consequences for saliva are applicable here as well.

It can be summarised that the capillary blood as an alternative for urine in clinical practice has not been researched sufficiently. Various medical fields show that ointments, for example, may have an influence on the analysis. Whether and to what extent it can influence the substance abuse requires more research. However, capillary blood is not above suspicion of providing protection against manipulation attempts.



Uncertainties regarding the above questions appear to be substantiated in scientific research:
Böttcher, Rönitz and Dahmen submitted the results of a study in 2014, whereby the objective of the study was to check whole blood as an alternative medium for EtG determination. They reached the conclusion that whole blood represents a possible alternative to urine for EtG evidence and thus “perhaps may be collected in future even as capillary blood”.