What are the side effects of heating pads?

September 22, 2025 •

4 min read

According to the Electrical Safety Foundation International, heating appliances should never be left unattended or used while sleeping. The potential side effects of heating pads can be serious, ranging from simple skin irritation to a more severe and lasting condition, so understanding the risks is critical for safe use.

Quick Summary

Heating pads, while effective for pain relief, carry risks including thermal burns, a reticulated skin discoloration called erythema ab igne, and other health issues, especially with prolonged use, high temperatures, or in individuals with reduced sensitivity. Following proper usage guidelines is crucial to prevent adverse reactions.

Key Points

Thermal Burns: Even low-temperature heating pads can cause second- or third-degree burns with prolonged exposure, especially if you fall asleep while using one.
Erythema Ab Igne: Chronic, low-level heat exposure can cause a net-like skin discoloration known as “toasted skin syndrome,” which can become permanent and is rarely associated with skin cancer.
Circulatory and Heart Issues: Heat can cause a temporary drop in blood pressure and an increase in heart rate, posing risks for individuals with cardiovascular conditions or a tendency for low blood pressure.
Increased Swelling: Applying heat to new injuries, swelling, or infections can worsen pain and prolong healing by increasing blood flow to the inflamed area.
Contraindications: Heating pads should be avoided by individuals with impaired sensation, vascular issues, cognitive impairment, or on areas with open wounds, bleeding, or malignancies.
Electrical Safety: Inspect your heating pad regularly for frayed wires and do not use it with extension cords or while sleeping to prevent fire and electrical shock risks.

Common Side Effects on the Skin

One of the most immediate and common side effects of heating pads is the potential for burns. These burns are not always caused by an extremely hot setting but can result from prolonged, lower-temperature exposure, especially when falling asleep with the pad on. The risk increases for individuals with impaired sensation, such as those with diabetes or neuropathy, who may not be able to feel when the heat is becoming damaging. These thermal burns can range in severity from mild redness and blisters to more serious second- and third-degree burns requiring medical attention.

A less known but equally important skin side effect is a condition known as erythema ab igne, or “toasted skin syndrome.” This is a persistent, reddish-brown, web-like rash that develops on the skin after long-term exposure to moderate, repetitive heat sources. Historically linked to proximity to open fires, it is now more commonly seen from chronic use of heating pads or laptops resting on the skin. While often benign, the skin damage associated with erythema ab igne can, in rare cases, lead to changes in skin cells and has been weakly associated with an increased long-term risk of certain skin cancers like squamous cell carcinoma. The discoloration can sometimes be permanent if the heat source is not removed.

Systemic and Circulatory Risks

Beyond localized skin issues, the use of heating pads can also have systemic effects on the body, particularly on the circulatory and cardiovascular systems.

Decreased Blood Pressure: Heat therapy can cause blood vessels to dilate, leading to a temporary drop in blood pressure. While this may be harmless for many, it can be problematic for individuals prone to orthostatic hypotension (dizziness upon standing) or those with underlying cardiac conditions.
Increased Heart Rate: To compensate for the increased blood flow to the heated area, the heart has to work faster, increasing the heart rate. For people with conditions like arrhythmia, this increased cardiac effort could pose a significant risk.
Increased Swelling: Despite popular belief, heat is not always the right choice for all types of inflammation. If used on a new injury (within the first 24-48 hours) or an inflamed infection, it can actually increase swelling and pain by increasing blood flow to the already-damaged or inflamed tissues.

Contraindications and Special Precautions

Certain individuals and conditions require extra caution or should avoid using heating pads altogether. Failing to heed these warnings can result in serious harm.

People who should use caution:

Pregnant individuals: While local, low-heat application is generally considered safe, placing a heating pad directly on the abdomen or overheating the core body temperature should be avoided, especially during the first trimester. It's best to consult a doctor before use.
Those with impaired sensation: People with conditions like diabetes or neuropathy, or those under the influence of sedating medications or alcohol, may not feel when the heat is too intense, leading to a higher risk of burns.
Individuals with vascular issues: Conditions such as peripheral vascular disease or deep vein thrombosis (DVT) can be aggravated by heat, which can increase blood flow and potentially dislodge a blood clot.
People with cognitive impairments: Dementia or other cognitive issues can interfere with a person's ability to remember safety precautions or to respond appropriately if the heat becomes too much.

Comparing Heat and Cold Therapy

Understanding the differences between heat and cold therapy is crucial for effective and safe pain management. A comparison can help in choosing the right tool for the right situation.


Feature	Heat Therapy (Heating Pad)	Cold Therapy (Ice Pack)
Mechanism	Dilates blood vessels, increases blood flow.	Constricts blood vessels, decreases blood flow.
Best for...	Chronic pain, muscle soreness, stiffness, cramps.	Acute injuries, swelling, inflammation, bruises.
Safety Risk	Burns (thermal or Erythema ab igne), electrical hazards.	Frostbite, skin damage from direct application.
Usage Window	15-30 minutes at a time; not while sleeping.	15-20 minutes at a time.
Contraindications	New injury, swelling, skin conditions, vascular issues.	Raynaud's phenomenon, poor circulation, cold hypersensitivity.

Safe Practices for Heating Pad Use

To minimize the risks and side effects, follow these essential safety tips when using a heating pad.

Use the Lowest Effective Setting: Start with the lowest heat setting and increase it only if necessary. Lower temperatures, while less intense, can still be effective over a safe period.
Limit Session Duration: Do not use the heating pad for more than 15-30 minutes at a time. Repeated, short sessions are safer and more effective than one long, continuous application.
Use a Protective Barrier: Always place a towel or piece of cloth between the heating pad and your skin to prevent direct contact, even with a pad cover.
Avoid Falling Asleep: Never sleep with a heating pad. If you may doze off, use a model with an automatic shut-off feature or set a timer to remind yourself to remove it.
Inspect the Equipment: Before each use, check the heating pad and cord for any signs of damage, such as cracks, frayed wires, or dark spots. If you find any damage, replace the product immediately.
Don’t Apply Pressure: Lying directly on the heating pad can intensify the heat and increase the risk of burns. Avoid putting extra weight or pressure on the heated area.

Conclusion

While heating pads provide effective relief for many common aches and pains, their side effects are a genuine concern that should not be overlooked. From the immediate risk of thermal burns to the long-term potential for erythema ab igne, improper use can lead to significant skin and circulatory issues. Understanding personal risk factors, such as existing health conditions, is crucial. By adhering to proper safety precautions, including using lower settings, limiting session times, and never falling asleep with the device on, you can harness the benefits of heat therapy while minimizing the potential for harm.

For more information on safe heat therapy, consult a reliable medical source like the American Academy of Physical Medicine and Rehabilitation.

Frequently Asked Questions

Yes, it is possible to get a burn from a heating pad even on a low setting, especially with prolonged exposure. This is why it is recommended to limit use to 15-30 minutes at a time and avoid falling asleep with the pad on.

Erythema ab igne is a rash or skin discoloration that appears as a web-like or fishnet pattern, resulting from repeated, chronic exposure to low heat sources like heating pads. While typically benign, in rare cases, prolonged heat damage has been associated with skin cell changes that may increase the risk of skin cancer.

Using a heating pad during pregnancy is generally safe when used correctly and locally, avoiding the abdomen. It is important to use a low setting and for short periods to prevent overheating the core body temperature. Always consult with a doctor first.

The recommended duration for using a heating pad is typically 15 to 30 minutes at a time. It is crucial to give your skin a break to prevent burns or irritation from prolonged heat exposure.

You should avoid using a heating pad on new or acute injuries, swollen or bruised areas, open wounds, and on skin with rashes or inflammation. It is also contraindicated for people with impaired sensation, diabetes, or certain vascular issues.

For mild burns, remove the heat source immediately, cool the area with cool (not cold) running water, apply aloe vera gel, and cover with a sterile bandage. For moderate burns with blisters or severe pain, or any burn that appears serious, seek immediate medical attention.

Yes, people with diabetes are at a higher risk of injury from heating pads. Impaired nerve sensation (neuropathy) can make it difficult to detect when the pad is too hot, leading to burns. Additionally, heat can affect blood glucose levels.