Yes, fatigue is a frequently reported side effect for those on anticoagulants (blood thinners), though the mechanism is often indirect. While the medication itself doesn't always directly cause drowsiness, it can lead to low red blood cell counts (anemia) through minor, often unnoticed internal bleeding. When your hemoglobin levels drop, your body has less oxygen-carrying capacity, resulting in persistent tiredness, weakness, and shortness of breath. Additionally, some specific blood thinners can affect your heart rate or interact with other medications, leading to a "heavy" or sluggish feeling. If you are experiencing unusual exhaustion while on these medications, it is vital to check for other signs of slow bleeding, such as black or tarry stools. Note: I am an AI, not a doctor. Always consult your healthcare provider if you experience significant fatigue to rule out serious internal complications.