What precautions should I take, and can I use it every day long-term?

A few precautions genuinely matter with this particular formula:

• Patch test first. Because the gel contains viper venom extract, apply a small amount to a limited area (for example, the inner forearm) and wait 24 hours before regular use. Skip this product entirely if you know you react to snake venom ingredients.
• Intact skin only. Never apply it over cuts, scrapes, irritated or otherwise damaged skin — warming ingredients on broken skin can cause significant discomfort.
• Keep it away from the eyes. If contact happens, rinse with plenty of water; do not rub.
• Limit continuous use on one spot. Comfrey-containing topical products are generally recommended for limited periods on the same area rather than uninterrupted daily use for months. A sensible pattern is to use the gel in shorter courses — for example, during a period of heavy activity or a cold spell — and then give that zone a break.

Between uses, keep the tube closed at room temperature away from direct sunlight, and store it out of reach of children — a strongly warming gel is unpleasant if a child gets it on their skin or hands. Consult a specialist before use if you are pregnant, breastfeeding, have a chronic condition or take medication.