Drug tolerance: how does it work?

What is drug tolerance? 

Drug tolerance is a pharmacological concept which corresponds to a reduced response to treatment when the drug is taken regularly. This may lead to reduced effectiveness of treatment.  

There are two main causes of drug tolerance: 

1. When a treatment is taken regularly, the body gradually becomes accustomed to it and succeeds in metabolising it (transforming it with the aim of eliminating it) more rapidly over time. This reduces the effectiveness of treatment.

1. The targets in the body that the treatment is intended to affect become accustomed to it and recognise it less, which also reduces the effect of the treatment.

Which medications can cause drug tolerance?

The drugs most likely to cause drug tolerance are: 

• Opioids, painkillers;  

• Corticoids, anti-inflammatory drugs;  

• Bronchodilators (salbutamol, terbutaline, formoterol, etc.); 

• Nitrates (drugs for angina pectoris, etc.); 
• Benzodiazepines, anxiolytic and hypnotic drugs (Xanax, etc.);  
  

To avoid this phenomenon with treatment by benzodiazepines, healthcare authorities recommend prescribing these medications for short periods of time (as short as possible) and at the lowest possible dose. In addition, this family of drugs should not be prescribed for more than 12 weeks.

What are the consequences and what can be done about it?  

The consequences are variable and depend on the class of treatment. 

For example, if drug tolerance develops towards opioid painkillers, this will certainly lead to an increase in pain. The patient is then less well relieved. 

A reduction in the effectiveness of your drug is a significant problem and should be reported to your doctor or pharmacist as soon as possible, so that the necessary steps can be taken. 

Solutions to this problem do exist. Thus, your doctor may decide to modify your treatment, if necessary. But in all cases NEVER CHANGE THE DOSAGE (never take a drug more often than was initially prescribed, or in larger quantities) OF A TREATMENT WITHOUT MEDICAL ADVICE. 

You must be vigilant, because sometimes the impression that you have become insensitive to a drug can also be caused by the progression of the disease. It is therefore essential to discuss it with your doctor.