Acute Bronchitis: This is the most common cause of hemoptysis after a forced cough, especially if the cough is severe and prolonged. The force of the cough can cause small blood vessels in the bronchial walls to rupture, leading to bleeding.

Pneumonia: Infections such as pneumonia can cause inflammation and potentially lead to hemoptysis, especially if the infection is severe or if there are underlying conditions like bronchiectasis.
Chronic Bronchitis: Part of chronic obstructive pulmonary disease (COPD), chronic bronchitis can lead to chronic cough and, occasionally, to hemoptysis due to the chronic inflammation and damage to the airways.
Asthma: Severe asthma attacks can lead to coughing fits that might result in hemoptysis, though this is less common.

Pulmonary Embolism: Although less common, pulmonary embolism can cause sudden onset of hemoptysis, especially if the embolism is large and causes infarction of lung tissue. This condition is life-threatening and requires immediate medical attention.
Lung Cancer: Hemoptysis can be a presenting symptom of lung cancer, particularly if the tumor erodes into a blood vessel. Given the potential for serious outcomes, it's crucial not to miss this diagnosis.
Tuberculosis (TB): TB can cause hemoptysis due to the destruction of lung tissue and erosion into blood vessels. It's essential to consider TB, especially in endemic areas or in individuals with risk factors.

Pulmonary Arteriovenous Malformation: A rare condition where there's an abnormal connection between arteries and veins in the lungs, which can lead to hemoptysis if the malformation ruptures.
Goodpasture Syndrome: A rare autoimmune disease that can cause bleeding in the lungs and kidneys, leading to hemoptysis.
Mitral Stenosis: A heart condition where the mitral valve narrows, potentially leading to increased pressure in the pulmonary veins and, rarely, to hemoptysis.