Fatigue and Weakness: A common symptom is persistent tiredness or weakness, even with adequate rest. 

Poor Immunity: Always getting sick, or taking a long time to recover from sickness.

Digestive Issues: Nausea, vomiting, diarrhea, or loss of appetite can occur. 

Nervous System Problems: Numbness, tingling, or pins and needles, especially in the hands and feet, are common. 

Mental Changes: Confusion, memory loss, or mood changes like depression can occur. 

Other Symptoms: Shortness of breath, heart palpitations, mouth sores, and vision problems can also occur

Pale Skin: B12 deficiency can lead to pallor due to impaired red blood cell production.