How to prevent phlebitis ?

Lifestyle changes.: Don't smoke. Exercise regularly. Avoid direct muscle injury to legs. Elevate legs and minimize salt intake to avoid swelling. Maintain low blood pressure.

Health & movement: Avoid obesity, tobacco, and standing or sitting immobile for more than a couple of hours. It 'trapped', such as when flying, pump your calf muscles by contracting and relaxing them a few minutes every hour or two and/or take a walk down the aisle. Compression stockings may be helpful, particularly for specific risks such as varicose veins. It is uncertain if there is any benefit from aspirin.

Treatment: If you have superficial venous reflux then you should have treatment for this. You can have an ultrasound to find out.

All are right: Don't smoke. Maintain healthy weight. Exercise. Avoid drugs that increase risk. Use graduated compression stockings. If you have varicose veins, get them treated. Elevate legs when possible. Stay well hydrated.