Cross tolerance

In pharmacology, cross tolerance is understood as the physiological tolerance to structurally similar active ingredients. In the case of two cross-tolerant substances A and B, repeated intake of substance A not only leads to tolerance to substance A itself, but also to substance B. The effect of substance A decreases over time with the same dosage, due to tolerance . The effect of the previously not ingested, structurally but similarly structured substance B decreases in the same sense over time, through cross tolerance .

Practical consequences

In medicine, if there is a change in the middle of treatment to one of the previously used cross-tolerant active ingredients, the initial dose of the new one must be set correspondingly higher. If a patient has a (cross) tolerance to an entire family of active substances, a more potent therapy may have to be chosen than in a patient who has not yet developed (cross) tolerance to the substance family.

Both legal and illegal drug users often have little knowledge of the cross-tolerance mechanism. If they notice a reduced effect compared to the previously experienced one, they often wrongly suspect the cause of this in a reduced active ingredient content of the drug used. If you then, as is not uncommon, increase the dose on your own, the physical stress and the addiction potential grow at the same time .

Well-known examples of cross-tolerant substances

• between the GABA-B agonists gamma-hydroxybutyric acid , baclofen , phenibut
• between the psychedelic serotonin agonists LSD , psilocybin / psilocin and mescaline
• between amphetamine , methamphetamine and ephedrine
• between the GABA-A agonists alcohol , benzodiazepines and barbiturates
• between the opioid agonists codeine , morphine and heroin
• between cytisine and nicotine

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !