Heating Pads and Heat Patches for Cramps: What Works and How to Avoid Burns

A heating pad, a microwavable wrap or a stick-on heat patch is often the first thing women reach for when cramps start. The evidence is fairly kind to heat, and the products are inexpensive. The main thing to get right is safety, because heat burns are easy to get without noticing.

What the research says about heat and cramps

A 2018 review pooled six randomized trials of heat for period pain without an underlying condition. Heat reduced pain compared with unheated placebo patches, and showed a trend toward working better than pain-relief pills in the trials that compared them.¹

The trials were small and some had a high risk of bias, so the authors called for better studies.¹ The heat used was moderate: patches or wraps around 39 to 40°C (about 102 to 104°F) worn for 8 to 12 hours, or warm infrared belts.¹

How burns happen

• Long contact, even on low. An analysis of burns from long heating pad use estimated that a pad on its low setting could cause a second-degree burn after roughly 12 to 20 hours of continuous contact.² Falling asleep on a pad can get you there.
• Skin you can’t fully feel. Doctors have reported serious burns in people with reduced sensation, such as from nerve damage.³ A similar burn was reported on the belly after abdominal surgery left the skin numb.⁴ If abdominal surgery left part of your belly numb, or you have numbness from diabetes, that skin may not warn you in time.
• Repeated heat. Using a heating pad or hot water bottle on the same spot day after day can cause erythema ab igne, a net-like brown or red rash. Mild cases fade over months once you stop, but severe skin changes can persist, and rarely skin cancer can develop in the affected area.⁵

Safer heat habits

1. Use the lowest setting that helps, with a cloth between the pad and your skin.
2. Don’t sleep on an electric pad. Choose one with an automatic shut-off, and set a timer.
3. Follow patch directions exactly, including the maximum wear time, and don’t wear a patch under a tight waistband or while lying on it.
4. Check your skin after each use for redness, blisters or a lacy rash, and give it a break if you see changes.
5. Skip heat on numb or broken skin, and ask your clinician first if you have diabetes, nerve damage or poor circulation.

When cramps need a visit

If cramps are new, getting worse, or come with heavy bleeding, especially in your 40s and early 50s, get checked. Conditions such as fibroids can cause both. Our articles on why cramps can be so bad and uterine fibroids explain what to ask.

Try: “My cramps have been worse over the past few months and heat isn’t enough anymore. What could be causing it, and what can we check?”

Period, Handled includes a Period Scorecard and a visit script. Use them to track pain, flow and what you’ve tried, and bring them to your appointment. See the book.