After an operation, heat is tempting: everything is stiff, and warmth usually helps stiffness. But a healing wound changes the rules, and the timing depends on the surgery.
The short version: ask your surgeon or therapist, and follow what they say over anything on this page. They know what was done inside and what stage your healing is at.
Why heat is held back at first
- Swelling. The early weeks after surgery involve inflammation and swelling. Heat increases blood flow and can add to it. Same reasoning as the 48–72 hour rule after an injury.
- The wound. Heat over an unhealed incision risks damage and infection. Skin around a fresh scar is fragile.
- Numbness. Surgery cuts small skin nerves, so the area around a scar is often numb for months. Numb skin can’t warn you that a pad is too hot. This is the most commonly missed risk, and the same one that makes diabetes with neuropathy so hazardous.
- Blood clots. The risk is raised after surgery, particularly joint replacements. A swollen, warm, tender calf needs a doctor, not a heat pad.
- Lymph node surgery. If nodes were removed or irradiated, heat stays off that limb for good, not just while you heal. See lymphoedema and heat.
A rough timeline
Indicative only. Your team’s instructions override this.
| Stage | Usual position |
|---|---|
| First days to about 2 weeks | No heat. Cold, elevation and your prescribed exercises. |
| Wound healed, stitches out, swelling settling | Ask your team. Heat may be allowed away from the scar. |
| 6 weeks onwards, stiffness is the main issue | Heat before exercises is often useful, with permission. |
| Months on, scar fully healed | Usually fine, with normal precautions. |
On managing swelling in those first weeks, see hot or cold compress for swelling. Once the scar is closed and you’re working on tightness, see tight scar tissue: where heat fits in scar massage.
When you’re cleared to use it
- Test the sensation first. With your eyes closed, have someone touch the area with something warm and something cool. If you can’t tell reliably, don’t use heat there.
- Keep it off the scar itself unless specifically told otherwise. Warm the muscles around it.
- Lowest setting, 10 minutes to start, with the cover on plus clothing.
- Check the skin every time, and stop if the area is more swollen or painful afterwards. Watch for toasted skin syndrome if you end up using it daily for months.
- Do your exercises straight after. That’s the point of the warmth. See “my physio said use heat”.
A few specifics
- Joint replacements. Numbness around the scar is common and persistent. Many surgeons prefer cold in the early months. Ask. See a stiff knee after knee replacement.
- Caesarean and abdominal surgery. Never over the wound. Heat on the lower back for back pain is usually fine once you’re comfortable. See heat after a C-section and pregnancy back and pelvic pain.
- Hand and wrist surgery. Hand therapy protocols are specific and often restrict certain movements for weeks. Follow the protocol. See stiff wrist after the cast comes off.
- Metalwork. Plates and screws don’t heat up from a heat pad, and the skin over them is the part to watch. See heat pads with metal implants, plates and a pacemaker.
- Shoulder surgery. A shoulder that stops moving stiffens fast; see frozen shoulder, but only within your surgeon’s protocol.
Contact your surgical team if…
- The wound is red, hot, swollen or oozing, or you have a fever. This can mean infection.
- The wound opens or bleeds
- One calf is swollen, warm or tender. Call 995 if that comes with breathlessness or chest pain.
- Pain is severe, burning and out of proportion, with colour changes and extreme sensitivity to touch
- You find any blistering or broken skin where a pad has been used
Full list of who should avoid heat: who should not use a heating pad.
The heat pad we use
We’ve supplied the Bremed BD7800 since 2010. It holds a steady temperature, covers a whole lower back and has a machine-washable cotton cover. Physiotherapy clinics in Singapore use it with their patients.
Clinically reviewed by: Nigel Chua (Hand Occupational Therapist) & Louise Yow (Physiotherapist). This article is general information, not a diagnosis. electricheatpad.com sells electric heat pads.
