It depends on the type of fast you are doing and the ingredients in the mushroom tincture.

Some types of fasts allow for the consumption of certain non-caloric beverages or supplements, while others require complete abstention from food and drink.

Type of fast:

If you are doing a water fast, for example, consuming a mushroom tincture would likely break the fast as it is not water.

On the other hand, if you are doing a dry fast (abstaining from both food and drink), consuming a mushroom tincture would also break the fast as it is a form of liquid.

If you are doing a different type of fast that allows for the consumption of non-caloric beverages or supplements, you may be able to consume a mushroom tincture without breaking the fast, depending on the ingredients.

Some mushroom tinctures may contain other ingredients such as alcohol or sweeteners, which could break a fast that only allows for the consumption of pure water.

Conclusion:

It is important to carefully read the rules of your fast and understand the ingredients in any supplements you are considering taking before making a decision.

If you are unsure whether a mushroom tincture would be allowed during your fast, it is always best to consult with a healthcare professional or the person who recommended the fast to you.