Megalis (Tadalafil 10mg) is a medication primarily used to treat erectile dysfunction and symptoms of benign prostatic hyperplasia. It works by increasing blood flow to the penis, which helps achieve and maintain an erection. Generally, Megalis (Tadalafil) does not have a direct impact on the immune system.

However, it's important to note the following:

1. Side Effects: Like any medication, Megalis 10mg may cause side effects. Some side effects are mild and temporary, such as headaches, indigestion, or back pain. Rarely, more serious side effects can occur, including allergic reactions or effects on heart health. If you experience unusual symptoms, it is important to contact your healthcare provider.

2. Drug Interactions: If you're taking other medications that affect your immune system (such as immunosuppressants), Tadalafil could interact with them, potentially influencing how your immune system works indirectly. Always inform your doctor about any other medications you're taking.

3. Pre-existing Conditions: If you have a pre-existing condition that affects your immune system (such as autoimmune diseases), it is crucial to discuss this with your healthcare provider before using Megalis. They can assess whether the medication could have any indirect effects in your specific case.

Overall, there isn't a direct effect on the immune system, but it’s always best to check with your healthcare provider if you have concerns or other underlying health conditions.