Thread Veins on the Legs: How Sclerotherapy Works and When It Is Not the Answer

Most people who ask us about leg veins have been looking at them for years before they mention it. They appear somewhere in the thirties, usually on the thigh or the outer calf, and they accumulate quietly enough that there is never an obvious moment to do something about them. By the time someone books, the question is rarely “can these be treated”. It is “why did nobody tell me what they were”.

They are worth understanding, because the visible vessel is sometimes the whole problem and sometimes the smallest visible part of a larger one. Telling those two situations apart is the first thing that happens at a consultation, and it is the reason a vein appointment at this clinic is with a doctor.

What thread veins are

Thread veins, spider veins and telangiectasia are three names for the same thing: tiny vessels sitting close enough to the skin surface to be visible, usually under 1mm across, red or purple, often arranged in the branching pattern that gives them their name. Reticular veins are their slightly larger relatives, blue-green, a little deeper, 1mm to 3mm, and frequently feeding the thread veins above them.

They form when the vessel wall loses its ability to hold its normal diameter and the vessel dilates. The reasons are mostly outside anyone’s control. Genetics is the strongest single factor. Oestrogen matters, which is why pregnancy and hormonal change are common trigger points. Prolonged standing loads the leg veins in a way that sitting does not, so the pattern shows up disproportionately in people who work on their feet. Ageing and previous trauma to the area both contribute.

What does not cause them is anything a cream can reach. The vessel is a structure in the dermis with its own wall and its own pressure, and no topical product penetrates to it or changes its calibre. That is not a criticism of skincare, it is a statement about depth.

The question that has to be answered first

A proportion of leg thread veins are a surface finding on an otherwise healthy venous system. Another proportion are the visible consequence of venous reflux further up, where valves in the deeper veins are no longer closing properly and pressure is being transmitted down into the superficial network.

That distinction changes everything. Treating the surface vessels while leaving reflux untreated gives a poor result that recurs, because the pressure driving the problem has not been addressed.

Certain findings mean the right next step is a vascular service rather than a cosmetic appointment. NICE guideline CG168, published in July 2013, sets out the referral criteria for varicose veins in the legs. It recommends referral where there are symptomatic primary or recurrent varicose veins, lower-limb skin changes such as pigmentation or eczema thought to be caused by chronic venous insufficiency, superficial vein thrombosis with suspected venous incompetence, a venous leg ulcer that has not healed within two weeks, or a healed venous leg ulcer. Bleeding varicose veins need immediate referral.

That guideline covers varicose veins and does not address thread veins, which is itself the useful point: thread veins on their own sit outside it. If you have any of the findings above alongside them, the veins are not the whole story and the assessment belongs with a vascular service that can perform duplex ultrasound.

Dr Shahe Boghossian, Medical Consultant and a GMC-registered doctor with a background in vascular surgery, assesses this at consultation before any treatment is offered. Where the picture points to underlying venous disease, the answer is a referral, and he will say so rather than treat the surface.

How sclerotherapy closes a vessel

Sclerotherapy is not a laser and it does not remove anything. A prescribed sclerosing solution is injected directly into the target vessel through a very fine needle. The solution irritates the lining of the vessel wall, which causes the wall to swell, the vessel to collapse, and the opposing walls to adhere to each other. The vessel is then closed. Over the following four to eight weeks the body reabsorbs the closed vessel and it stops being visible.

Two things follow from that mechanism, and both are worth knowing before booking.

The first is that nothing happens on the day. The vessel closes during the appointment but clearance is a reabsorption process on the body’s timescale. Judging the result at two weeks means judging it before it has happened.

The second is that each vessel is treated individually. There is no single pass that covers a leg. That is why sessions are planned around the pattern and distribution present rather than sold as a fixed package, and why most people need between two and four of them, spaced so that each round can clear before anyone decides what remains.

What the evidence supports

The Cochrane review Sclerotherapy for lower limb telangiectasias (Schwartz and Maxwell, Cochrane Database of Systematic Reviews, 2011) pooled the randomised trials available at the time. Its conclusion was that the sclerosing agents studied were superior to a normal saline placebo, and that the evidence did not show superior efficacy or patient satisfaction for any one agent over another.

The reviewers were also clear that methodological quality across the included studies was poor, which prevented firm conclusions about optimal concentrations or which agent produces fewest side effects. That is an accurate summary of where the field sits, and it is more useful to a patient than a percentage would be. Sclerotherapy works. The literature does not support fine distinctions between the agents used, and anyone claiming otherwise is ahead of the evidence.

What to expect afterwards

The injections themselves are described by most people as a mild sting or burning that settles quickly. The needle is very fine and the treatment is generally well tolerated without anaesthesia.

Compression stockings are worn afterwards for the period Dr Shahe advises. Walking immediately after each session is encouraged rather than merely permitted, because calf muscle activity supports venous return through the treated area. Most people return to normal activity the same day, so plan clothing you can get over a dressing and drive in comfortably.

Expect some bruising, redness and mild swelling around the injection sites. Two specific effects are worth naming because they are common enough to surprise people who have not been told:

Hyperpigmentation. Brown staining along the line of the treated vessel, caused by haemosiderin from broken-down blood. It is reported across the sclerotherapy literature and usually fades over months, though in some people it persists.

Matting. The appearance of a fine network of new, very small vessels near a treated area. It is recognised in the Cochrane review as telangiectatic matting or neovascularisation. It sometimes settles on its own and sometimes needs further treatment.

Avoid hot baths, saunas and prolonged sun exposure to the treated area for the period recommended after each session.

Where sclerotherapy is the wrong choice

Varicose veins. Larger, deeper vessels are a different clinical problem requiring duplex ultrasound assessment and a different pathway. Sclerotherapy at this clinic is for thread veins, spider veins and reticular veins.

Facial thread veins. The vessels on the nose and cheeks are treated with light rather than injection. Laser vein removal is the route there, and the vein removal concern page sets out why the two areas are handled differently.

Where the medical history rules it out. Treatment is not appropriate in pregnancy, or where there is a history of deep vein thrombosis, a known allergy to sclerosing agents, active infection or skin disease in the treatment area, or significant immobility. A full medical history and vascular assessment at consultation determines suitability.

Where the expectation is a single clearance. Results in treated vessels are long-lasting, but new vessels can develop over time, particularly with hormonal change or prolonged standing. This treats what is there. It does not change the tendency that produced it.

Booking and getting to us

Sclerotherapy starts from £200 per area, and the treatment page carries the current price and the booking link. Every course begins with a consultation and vascular assessment with Dr Shahe before any treatment is offered.

The clinic is at 65 London Road, Newark-on-Trent, NG24 1RZ, with free parking at the front. Because sessions are spaced to let each round clear, the commitment runs over months while the number of visits stays low. Patients travel to us from Balderton, Farndon, Collingham, Southwell, Bingham and Ollerton, and from Lincoln, Grantham and Sleaford.

Frequently asked questions