I take once a month intramuscularly Vitamin B12 500mcg WZF, can I simultaneously use Solgar B complex or Swanson B complex capsules?

You can use Solgar or Swanson capsules if your doctor tells you to. If you think that the use of a specific dietary supplement is necessary for you, I encourage you to consult your doctor. Before starting to use vitamin supplements, it is important to read product labels and consult your doctor for more personalized and safe recommendations. You can read more about whether you need to supplement vitamins and minerals in the text: https://www.gdziepolek.pl/artykuly/czy-trzeba-suplementowac-witaminy-i-mineraly If you are unable to get to your primary care doctor, the GdziePoLek.pl service also allows you to obtain a teleconsultation with a doctor: https://www.gdziepolek.pl/telekonsultacja