Protein powders consist of isolated protein from various sources like milk, eggs, peas, spirulina, soy, rice, and hemp.  They are generally safe to consume and are a healthy source of protein. They offer a convenient way to meet your daily protein needs and must be used as part of a larger diet, not as a meal replacement.
However, you might have allergies or intolerance to the protein source, which might render the protein ineffective. For instance, those with a soy allergy cannot consume soy protein. It is advisable to be mindful of this when choosing a protein powder.