Swimming usually leaves you invigorated and refreshed, but sinus headaches that result from swimming make you feel as if you are still underwater after you finish your workout. Plugged sinus cavities lead to infections and increased pressure and headaches. Repeated sinus headaches mean you might need to change your swimming regimen, or the location where you swim.Sinus headaches originate from pressure and pain in the sinuses caused by sinusitis. Sinusitis is a condition involving irritated and inflamed nasal passages. Inflamed and blocked sinus cavities behind your cheeks, eyes and jaw further lead to infection of the canals. Sinusitis and sinus headaches sometimes follow upper respiratory infections or cold viruses. You overcome the viral infection, but opportunistic bacteria takes advantage of your weakened immune system following colds or flu, and you might need medical treatment to get rid of the bacterial infection.Swimming and diving increases your risk of sinusitis in part because of the pressure changes you experience when you go underwater,Your sinus canals block up and the pressure change in your sinuses creates pain. Swimming pool chemicals might cause you nasal tissues to redden and swell. When mucus thickens and plugs your sinuses, any viruses or bacteria in the pool water introduced into the canals grow and replicate, causing infection.Mild sinus headaches benefit from home treatments. You need to reduce the swelling and inflammation of your nasal passages in order to relieve the pressure that leads to sinus headaches. Saline or salt-water sprays irrigate nasal passages and wash out any irritating pool chemicals. Over-the-counter pain relief medication can help relieve some swelling and pain. Avoid exerting yourself or going in the pool until you fully recover from the headache and the sinusitis that causes it. Wearing nose clips prevents water from getting into your sinuses, and avoiding diving deep in the water prevents the pressure changes that cause blocked sinuses.