Varithena is FDA-approved and has a well-documented safety profile, but like any medical procedure, it carries real risks that are worth understanding before you decide to move forward. In clinical trials involving over 1,300 treated patients, the most serious concern, deep vein thrombosis (DVT), occurred in 2.8% of cases. No cases of pulmonary embolism were diagnosed.
How Varithena Works
Varithena is a prescription injectable microfoam used to treat varicose veins. The active ingredient damages the inner lining of the targeted vein, causing it to collapse and eventually be absorbed by the body. Blood reroutes through healthier veins. The procedure is done in a doctor’s office, guided by ultrasound, and typically takes under an hour with no general anesthesia.
One distinction that matters for safety: Varithena uses a proprietary low-nitrogen gas blend to create its foam, rather than room air. Older foam sclerotherapy techniques that used room air have been linked to serious neurological events including stroke, seizures, and transient ischemic attacks. In Varithena’s clinical trials, none of those events occurred across all 1,333 treated patients.
Common Side Effects
Clinical trial data from 437 patients receiving Varithena showed these side effects occurring more frequently than in patients who received a placebo:
- Leg pain: 14.9% of patients (compared to 9.3% with placebo)
- Injection site clotting (retained coagulum): 10.5%
- Bruising or injection site bleeding: 8.7%
- Superficial vein inflammation: 9.2%
- Limb discomfort: 7.3%
- Tenderness or injection site pain: 6.9%
Most of these are localized reactions that resolve within the first few weeks. The bruising, tenderness, and discomfort at the injection site are essentially what you’d expect from any procedure that deliberately irritates a vein. They’re uncomfortable but not dangerous.
DVT and Blood Clot Risks
The most significant safety concern with Varithena is the risk of blood clots. In the pooled clinical trial data, DVT was detected by ultrasound in 2.8% of treated patients (38 out of 1,333). In the controlled comparison group receiving the 1% dose, the rate was 4.7%. These clots were identified through routine post-procedure ultrasound screening, meaning some were detected before causing symptoms.
A related finding: 5.5% of patients in the pooled data experienced a clot that started in the treated superficial vein and extended into a deeper vein at the groin. These were non-occlusive, meaning they didn’t fully block the vein.
You’re at higher risk for clot-related complications if you have reduced mobility, a personal history of DVT or pulmonary embolism, recent major surgery within the past three months, prolonged hospitalization, or current pregnancy.
Neurological and Visual Safety
This is where Varithena’s safety record stands out compared to older foam treatments. In the pivotal clinical trials, no strokes, seizures, or transient ischemic attacks were reported. Nervous system symptoms like headache or dizziness occurred at similar rates in patients receiving Varithena (7.4%) and those receiving placebo (8.6%), suggesting these weren’t caused by the treatment itself.
One patient in an earlier safety study reported “twinkly lights” in their peripheral vision about an hour after treatment, lasting 20 seconds. A follow-up eye exam was normal. Brain MRIs, neurological exams, and cardiac monitoring across the trial population showed no new abnormalities after treatment. Out of all 1,333 patients treated with Varithena, none experienced a clinically important neurological or visual event.
Long-Term Safety at One Year
Follow-up data from the VANISH-2 study tracked patients for a full year after treatment. At the 12-month mark, there were no new blood clot events, no pulmonary emboli, and no cases of post-thrombotic syndrome (chronic pain and swelling that can follow a DVT). Patients who had experienced a clot earlier in the study showed no recurrence and no lasting complications at one year. No serious adverse events related to the drug were reported at the one-year follow-up.
Pregnancy and Breastfeeding
The limited published data on use during pregnancy has not identified risks for birth defects, miscarriage, or harm to the mother or fetus. Animal studies at doses up to 13.5 times the maximum human dose showed no developmental problems. That said, there’s generally little reason to treat varicose veins during pregnancy, since pregnancy-related varicose veins often shrink on their own after delivery.
For breastfeeding, there’s no data on whether the drug passes into breast milk. The FDA labeling suggests pumping and discarding breast milk for up to 8 hours after treatment as a precaution.
What Recovery Looks Like
The post-procedure period plays a role in safety outcomes, particularly for clot prevention. You’ll leave the office with bandages and compression stockings, which stay on continuously for the first 48 hours. After that, you can shower and reapply compression socks, wearing them day and night for the first 14 days. Walking is encouraged, but strenuous activity is typically restricted in the early recovery window. Following the compression protocol matters because it helps the treated vein stay closed and reduces the risk of clotting complications.