Well the tablets are considered more convenient by doctors n patients, they have a more steady hormone level then shots, but they have to go through the liver and this can cause strain to the liver
Shots bypass the liver so the liver won't go through any stress, they also are a little less steady when it comes to hormone levels, then there's the pain of the shot and a slight risk of infection from the needle.
The side effects are both the same, if any.
Common side effects are: Abnormal hair growth; breast tenderness; changes in sex drive; cramps; dizziness; flushing; hair loss; headache; lightheadedness; nausea; pain, swelling, or redness at the injection site; reduced tolerance to carbohydrates; stomach bloating and upset; swelling; vaginal infection; weight changes.
Seek medical attention right away if any of these SEVERE side effects occur:
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); abnormal vaginal bleeding; breast lumps; calf pain or tenderness; changes in vaginal bleeding (eg, spotting, breakthrough bleeding, prolonged bleeding); changes in vision or speech; chest pain; confusion; coughing of blood; mental/mood changes (eg, depression, memory loss); numbness of an arm or leg; one-sided weakness; pain, swelling, or tenderness in the stomach; problems with contact lenses (eg, changes in fit); severe headache, dizziness, fainting, or vomiting; sudden shortness of breath; swelling of hands or feet; unusual vaginal discharge, itching, or odor; weakness of an arm or leg; yellowing of the skin or eyes.
So needless to say DON'T SELF MEDICATE. If your buying online be shore to tell your doctor what your going to be using and they WILL give you proper medical supervision and they will not share you medical information with anyone without your consent.