How is it possible that Mydocalm has had the opposite effect?

Although Mydocalm is typically prescribed to reduce muscle tension and relieve pain, in some cases you may experience an unusual reaction like the one you experienced. Each body may react differently to medications. In your case, Mydocalm may have had a paradoxical effect by increasing muscle tone instead of decreasing it.

Mydocalm is usually prescribed in doses of 50 to 150 mg, 3 times a day. If you were given a single dose of 150 mg, it may have been too much for your body, causing unwanted effects.

In this case, you should contact the doctor who prescribed the medicine, who may decide to change the dose, switch to another medicine or suggest alternative treatments for back pain. If you are unable to consult your doctor, you can use the teleconsultation here:

https://www.gdziepolek.pl/telekonsultacja

I encourage you to report the symptoms you experience to your doctor, as well as to report the occurrence of an adverse effect of the preparation. Reporting side effects allows you to increase control over medicines available on the market. We wrote more about how and why to report side effects in the article: 

https://www.gdziepolek.pl/artykuly/jak-i-dlaczego-zglaszac-dzialania-niepozadane