These three conditions are frequently linked and highly treatable. For vitamin D deficiency, a daily Vitamin D3 (cholecalciferol) supplement is typically recommended. For low testosterone, your doctor may prescribe testosterone replacement therapy (such as topical gels, patches, or injections) after a blood test. For erectile dysfunction, daily or as-needed medications like sildenafil or tadalafil are very effective. Because testosterone therapy requires careful monitoring and erectile dysfunction medications can interact with other drugs, it is important to consult a healthcare provider or urologist to safely coordinate these treatments and find the right dosages for you.