Sclerotherapy effectively treats varicose and spider veins. It's often considered the treatment of choice for small varicose veins.

Sclerotherapy involves injecting a solution directly into the vein. The sclerotherapy solution causes the vein to scar, forcing blood to reroute through healthier veins. The collapsed vein is reabsorbed into local tissue and eventually fades.

After sclerotherapy, treated veins tend to fade within a few weeks, although occasionally it may take a month or more to see the full results. In some instances, several sclerotherapy treatments may be needed.

Sclerotherapy is often done for:

• Cosmetic purposes — to improve the appearance of varicose and spider veins

The procedure can also improve related symptoms such as:

• Aching
• Swelling
• Burning
• Night cramps

If you're pregnant or breast-feeding, doctors recommend waiting to have sclerotherapy done.

Sclerotherapy results in few serious complications.

Temporary side effects

Some side effects that may occur at the site of the injection include:

• Bruising
• Raised red areas
• Small skin sores
• Darkened skin in the form of lines or spots
• Multiple tiny red blood vessels

These side effects usually go away within a few days to several weeks. Some side effects can take months or even years to disappear completely.

Side effects that may require treatment

Other complications are less common but may require treatment. These include:

• Inflammation. This is usually mild but may cause swelling, warmth and discomfort around the injection site. Your doctor may suggest an over-the-counter pain reliever such as aspirin or ibuprofen (Advil, Motrin IB, others) to reduce the inflammation.

• Blood clot. A lump of clotted blood may form in a treated vein that may require drainage. Rarely, a blood clot may travel to a deeper vein in your leg (deep vein thrombosis).

  Deep vein thrombosis carries a risk of pulmonary embolism (a very rare complication of sclerotherapy), an emergency situation where the clot travels from your leg to your lungs and blocks a vital artery. Seek immediate medical care if you experience difficulty breathing, chest pain or dizziness, or you cough up blood.

• Air bubbles. Tiny air bubbles may rise in your bloodstream. These don't always cause symptoms, but if they do, symptoms include visual disturbances, headaches, fainting and nausea. These symptoms generally go away, but call your doctor if you experience problems with limb movement or sensation after the procedure.
• Allergic reaction. It's possible that you may have an allergic reaction to the solution used for treatment, but this is uncommon.

Before the procedure, your doctor performs a physical exam and gathers your medical history.

Physical examination

Your doctor will:

• Evaluate the involved veins
• Check for any underlying blood vessel disease

Medical history

Your doctor will want to know your medical history, including asking about any:

• Recent illnesses or existing medical conditions, such as a heart condition or a past history of blood clots
• Medications or supplements you take, especially aspirin, ibuprofen (Advil, Motrin IB, others), naproxen sodium (Aleve, Anaprox Ds), blood thinners, iron supplements or herbal supplements
• Allergies
• Previous treatment for varicose veins and the results of the treatment

If you take aspirin, ibuprofen, naproxen sodium or blood thinners, your doctor may instruct you on how to stop taking the medication for a certain amount of time before the procedure, to reduce the chances of bleeding.

Ultrasound

Depending on which veins are involved, your doctor may request ultrasound imaging on the veins in your legs. Ultrasound is a painless procedure that uses sound waves to produce images of structures inside the body.

The day before

Before the procedure, avoid shaving or applying any lotion to your legs. (Don't shave or use lotion after the procedure until the injection site is healed either.) Wear loose, comfortable clothing to your appointment. You might even consider wearing a pair of shorts so that your legs are exposed.

Sclerotherapy is typically done in your doctor's office and doesn't require anesthesia. It generally takes less than an hour to complete.

During the procedure

For the procedure, you'll lie on your back with your legs slightly elevated. After cleansing the area to be treated with alcohol, your doctor will use a fine needle to slowly insert a solution into the appropriate vein.

The solution, usually in liquid form, works by irritating the lining of the vein, causing it to swell shut and block the flow of blood. Some solutions contain a local anesthetic called lidocaine.

Eventually, the vein will become scar tissue and disappear. Sometimes a foam version of the solution may be used, particularly when a larger vein is involved. Foam tends to cover more surface area than liquid.

Some people experience minor stinging or cramps when the needle is inserted into the vein. If you have a lot of pain, tell your doctor. Pain may occur if the solution leaks from the vein into surrounding tissue.

Once the needle is withdrawn, your doctor applies compression and massages the area to keep blood out of the injected vessel and disperse the solution. A compression pad may be taped onto the injection site to keep the area compressed while your doctor moves on to the next vein.

The number of injections depends on the number and size of veins being treated.

After the procedure

You'll be able to get up and walk around soon after the procedure. Walking and moving your legs is important to prevent the formation of blood clots.

You'll be asked to wear compression stockings or bandages — usually for about two weeks — to maintain compression on the treated veins.

Most people return to their normal activities on the same day, but it may be wise to have someone drive you home after the procedure. Your doctor will probably advise you to avoid strenuous exercise for two weeks after the procedure.

You'll also want to avoid sun exposure to the treated areas during that time. The inflammation caused by the injections combined with sun exposure can lead to dark spots on your skin, especially if you already have a dark skin tone.

If you were treated for small varicose veins or spider veins, you can usually expect to see definitive results in three to six weeks. Larger veins may require three to four months. However, multiple treatments may be needed to achieve the results you want.

Veins that respond to treatment generally don't come back, but new veins may appear.

Your doctor will likely schedule a follow-up visit about a month after the procedure to determine how well the procedure worked and if you need more sessions. Generally, you need to wait about six weeks before undergoing another sclerotherapy session.