If you use a sports cream, like Icy Hot Advanced, with a heating pad, can the cream be absorbed through the skin and cause side effects?
At a glance
- External heat sources (e.g. heating pads or blankets) should not be used over topical products like Icy Hot.
- The application of heat increases blood flow, skin breakdown and drug absorption. These all increase the risk of side effects, including serious burns.
You should not use any sort of external heart source, such as a heating pad, with topical analgesics, Icy Hot products included. Doing so can significantly increase the risk of side effects.
In fact, the FDA has released numerous safety alerts warning about the risk of rare, but serious burns with the use of over the counter topical analgesics. The safety alerts specifically mention to avoid using a heating pad over these products:
"When applying OTC topical muscle and joint pain relievers to the skin, do not bandage the area tightly and do not apply local heat (heating pads, lamps, hot water in bags or bottles) because doing so can increase the risk of serious burns."
Now, 'Icy Hot' is a brand name which includes a family of products, many of which contain different active ingredients.
The product you mention in your question, Icy Hot Advanced, contains two:
- Menthol 11%
- Camphor 16%
While serious burns with topical products that contain these ingredients are rare, numerous case studies have reported them. One such case study, which detailed a serious burn, reported the following:
"This patient experienced full-thickness skin and muscle necrosis as well as persistent interstitial nephritis as a result of topical application of methyl salicylate and menthol followed by use of a heating pad, despite the manufacturer's warning against the use of heating pads."
The overall point is that using heating pads over topical analgesics increases the risk of side effects, which include burns, dermatitis and skin/muscle necrosis.
The packaging of Icy Hot products (and other topical analgesics) clearly state not to use heating pads for this reason.
Heating Pads And Absorption
When talking about drugs that are applied to the skin, they are generally divided in to two types:
A 'topical' product is where the intended site of action is to the skin itself. Icy Hot products that contain menthol are 'topical' products.
A transdermal product is intended for systemic absorption (i.e. into the blood stream). An example transdermal product is Duragesic, which contains the potent opioid fentanyl.
Applied heat over both of these types of products can increase the risk of serious side effects.
For drugs like fentanyl, numerous case studies have been published where the use heating pads or blankets were thought to play a significant role in dangerous overdoses.
For 'topical' products, as discussed above, heating pads have been linked to an increased risk of burns and associated side effects.
So, what is happening when you apply heat over a drug product on the skin? A lot!
Heating the skin causes:
- Vasodilation and increased blood flow
- An acceleration of skin breakdown
- Increased skin perfusion
All of these effects are of concern with the use of topical products.
Additionally, when we are talking about certain prescription drugs where the active ingredient is contained in a 'drug-reservoir', (like certain fentanyl patches), the application of heat can increase the rate of drug release.
Going back to Icy Hot, the recommendation to avoid placing direct heat over the application site applies to all their products, not just the ones that contain menthol.
- Icy Hot Manufacturer Website. Icy Hot
- Heat effects on drug delivery across human skin. PubMed
- Heat-associated increase in transdermal fentanyl absorption. Oxford Academic
- Local necrosis and interstitial nephritis due to topical methyl salicylate and menthol. PubMed
- Salicylate Poisoning Potential of Topical Pain Relief Agents: From Age Old Remedies to Engineered Smart Patches. USC
- Acute auditory and vestibular symptoms associated with heat and transdermal lidocaine. PubMed