A human being has a symmetrical face in general. The appearance and size of facial structures on the one side is roughly the same on the other side. Small differences are normal and can be attributed to genetics, age or body weight. When one side is substantially different to the other side, compared to a small but normal difference between the two sides, then it is possibly time to consult with a doctor to rule out any serious causes of the asymmetry.

One Side of Face Swollen: Why?

1. Physical Trauma

Facial injuries are the most common reason for one side of the face swelling. These injuries include car accidents, insect stings or bites, falls on the face, blunt force trauma received in an assault, sunburn on one side of the face, surgical procedures on one side, fractured facial bones. After a facial injury, fluid accumulates to protect the injured tissue. The area becomes inflamed with pain, tenderness and redness. The skin may exhibit some bruising as well.

2. Infections

Bacteria or other microorganisms may infect the tissues of the face. They may invade the superficial layers of the skin or even deeper tissues like muscles or bones. Some types of infection that may cause swelling on one side of the face are:

• Sinusitis–affects the nasal sinuses
• Abscess–can be on the gum, near the tonsils or in a tooth
• Osteomyelitis–infection of bones of the face
• Ocular infections like blepharitis, conjunctivitis or keratitis
• Cellulitis–a type of skin infection
• Parotitis–inflammation of the parotid gland
• Lymphadenitis–inflammation of the lymph glands

3. Allergies

Some cosmetics could elicit one side of face swollen. Allergies to insect bites or stings, some drug allergies or allergic rhinitis may also present with one-sided facial swelling. Certain medications like some antibiotics or steroidal treatments may cause facial swelling. If you suspect this, seek the advice of your doctor.

4. Muscle Deformities

Some medical conditions like Bell's palsy may cause a complete or partial paralysis of facial muscles, thus distorting the normal definition of the face. Muscle enlargement on one side can occur if the person clenches their jaw on one side or chews only on the other side.

5. Tumors

Tumors may occur on one side of the face. They may be malignant or benign and affect the muscles, skin, connective tissue, bone or lymph vessels in the skin.

6. Medical Conditions

Medical conditions like kidney, liver, heart failure may cause one sided swelling on the face. Obesity and malnutrition can also distort the facial symmetry. The lack of sufficient nutrients causes facial swelling and distended abdomen.

7. Facial Surgery

Any type of surgery to the facial area will result in accumulation of fluids in the face. Usually after surgery you will be given medication to relieve it.

How to Relieve Swelling on One Side of Face

Depending on the source of one side of face swollen, you can either get treatment or minimize the facial swelling by:

• Hot compresses will improve blood circulation bringing with it all the elements in the blood that can speed up the healing process. A clean cloth dipped in some hot water and applied to the area for up to 30 seconds will do. You can repeat this action up to 3 times per day.
• Cold compresses will reduce swelling to the area and decrease the pain caused by the inflammation. You can use ice wrapped in a clean towel or even some frozen peas wrapped in a thin cloth. Hold the cold compress to the affected area for up to 30 seconds and repeat during the day as necessary.
• Avoid a high sodium intake since sodium causes facial puffiness by retaining fluids within the tissues.
• Regular steam inhalations will loosen mucus in the sinuses so that they are easily expelled. This will reduce the congestion and swelling in the face.
• ŸPotatoes have been used for generations to combat the effects of pain and inflammation. Place raw potato slices, which have been peeled, against the swelling. The potato may also be cooked, mashed and wrapped in a clean cloth. This may be used as a hot compress as well.
• Avoid the cosmetics or facial products that trigger your allergies. This may take some investigation on your part to figure out what is causing one side of face swollen.
• ŸA bee sting can be treated with a cold compress. If other complications crop up, like difficulty in breathing, seek medical attention immediately, as you could be having an anaphylactic response to the bee sting. You may require an epinephrine injection to halt your body's reaction to the allergen. In future, you may have to carry an epinephrine kit with you at all times to prevent having an anaphylactic shock after a bee sting.
• Some people believe in applying egg whites to the swollen areas. Soaked tea bags are also believed to relieve swelling. 
• Uncomplicated swelling of the face may only require a course of antihistamines to control the allergy.
• Seek medical attention from your doctor or dentist if you suspect an infection. All that may be required is a course of antibiotics to eliminate the infection and relieve the swelling.