Is there a Link between Salicylate Sensitivity and Itchy Skin?

by | Jan 11, 2023

Are you prone to red, blotchy, itchy skin and have tried various treatments to no/minimal avail? Salicylate sensitivity may be the answer.

While the majority of people don’t have a problem with salicylate-containing foods or medicines, research has shown that 60% with of adults with food-induced itchy rashes and 51% of adults with eczema may be sensitive to salicylates (1).

What are salicylates?

Salicylates (suh-lih-suh-lates) are a group of chemicals derived from salicylic acid. They are a naturally occurring chemical produced by plants, acting as the plant’s immune system, reducing the risk of pathogens invading and defending against environmental stress.

Due to their antifungal and antibacterial properties, salicylic acid and its derivatives are often used as preservatives in processed foods, condiments, cosmetics, and toiletries. Those without salicylate sensitivity can consume salicylates without harm, it’s only when consumed in very high quantities that they can be dangerous. Unfortunately for a select few, even a small amount of salicylate exposure can be detrimental, leading to undesirable symptoms and a diminished quality of life.

What are some common causes of itchy skin?

Urticaria: also known as hives, this skin condition is characterised by a raised, itchy rash (presenting as larger bumps not generally filled with fluid) that appears on the skin. It can appear in different parts of the body and present in different sizes. Urticaria occurs usually as a result of an allergic reaction, but they can also have other triggers including diet, infection, autoimmune, heat, cold and stress (6).

Eczema: also referred to as atopic dermatitis, eczema is one of the most common inflammatory skin diseases. It is characterised by itch, skin inflammation (most often as dry rough pink plaques on the skin / raised bumps that may be filled with fluid) and skin barrier abnormality. While the cause of eczema is still unknown, hypotheses include a chronic problem rooted in the immune system, a strong genetic link (e.g. genetic mutation that causes skin barrier to not work properly) and environmental factors (e.g. exposure to certain fabrics, foods and skin care products).

Psoriasis: a chronic, painful skin disease that presents as scaly, itchy patches on the skin, most commonly on the knees, elbows and scalp. The condition appears to be cyclical, with rashes flaring for a few weeks, then subsiding for weeks or months at a time before reappearing again. There are several types of psoriasis, each with its own specific symptoms. While the cause of psoriasis isn’t well understood, research shows it may be an immune system problem that causes skin cells to grow at a rapid rate, resulting in dry, scaly patches. There is also research to suggest genetic and environmental factors may play a role (7).

What evidence is there to show that salicylates may contribute to itchy skin?

Research into salicylate sensitivity and its link to the above conditions is still in its infancy. While scientists haven’t yet been able to ascertain a causal link between salicylates and itchy skin, there is some interesting research highlighting links between the two.

Urticaria

It’s well documented that Aspirin (a derivative of salicylic acid) can exacerbate urticaria, with approximately 20-30% of patients having their symptoms heightened by ingesting the drug (8).

For example, a single-blind, placebo-controlled study with aspirin showed that nearly a quarter of children and adolescents with chronic spontaneous urticaria were hypersensitive to aspirin (9).

Another study looking at the effects of aspirin in chronic urticaria (5) was conducted on 70 patients. 20 of these patients experienced an exacerbation of their condition shortly after taking aspirin, the symptoms of which abated to their pre-aspirin levels a few days after stopping the drug. Test doses of aspirin varying from 5-15 grams were then given to the patients and 80% showed an increase in their rash. The patients were then tested with sodium salicylate which gave the same results as aspirin.

The question remains though as to whether reducing salicylates in the diet is justified in the management of the skin condition.

A dietary investigation (4) was conducted in 1349 patients with recurrent idiopathic urticaria (RIU) and angioedema using an elimination diet and double-blind challenge protocol. Patients undertook a strict elimination diet and those who experienced a significant reduction or complete relief of symptoms for 5 consecutive days after a minimum of two weeks on the diet were given challenge capsules containing either a challenge chemical (e.g. salicylates) or a placebo. Patients kept a detailed record of their diet, challenge capsule taken and symptoms experienced. Results showed that 54.9% of patients experienced urticaria when challenged with acetylsalicylic acid and 45% when challenged with sodium salicylate, indicating that food chemicals such as salicylate are important precipitants of RIU.

A prospective, non-randomised, baseline-controlled intervention study (8) was conducted to see whether a personalised low salicylate diet (PLSD) was effective in the reduction of urticaria symptoms (along with asthma and rhinosinusitis) with hypersensitivity to aspirin. After following a PLSD diet, 86.96% of patients with diagnosed urticaria declared a remission of symptoms. In 8.70% of patients, the severity of symptoms did not change while one patient declared an increase in perceived symptoms.

Conversely, one study found only 19% urticaria patients reacted severely to challenge capsules containing food additives and salicylic acid (6), highlighting the need for more research in the area.

Eczema

A dietary investigation (4) in patients experiencing conditions such as migraine, IBS, asthma and eczema was conducted. Patients were placed on a strict elimination diet (similar to that of the dietary investigation into recurrent idiopathic urticaria), with slight modifications including the exclusion of wheat and milk products. The challenge set was made double-blind with placebos. Of the 80 patients with eczema that took part in the trial, 51% reported a reaction to salicylates.

Another study (10) investigated the social patterning of eczema, i.e., a higher prevalence of eczema was found to be associated with a higher social class. Hypotheses include differences in lifestyle factors (e.g. use of mediations, carpets, dust mite populations, overuse of soaps, contact with pets, etc.), prolonged breastfeeding, and antibiotic use in the first year of life. One factor not mentioned, but made me think, perhaps increased fruit and vegetable consumption (thus higher levels of salicylates) by more economically advantaged children (11) could be a contributing factor in eczema prevalence?

Unfortunately, there is little peer-reviewed evidence to support the use of low-salicylate diets in treating eczema. More research is needed to really ascertain if there is a link between the two.

Psoriasis

A study (2) looking at general pustular psoriasis in childhood (a rare occurrence) used a cohort of 13 children suffering the condition to analyse their psoriasis triggers. One of the twelve children had aspirin listed as a trigger. The researchers followed the child for 19 years into adulthood and found that their psoriasis improved markedly when eliminating aspirin.

There’s also a case study (3) of a young boy with pustular psoriasis who ended up in hospital due to the condition. On several occasions, the boy spent spring in different parts of the country – sometimes in Ohio and at other times Pennsylvania. During the spring in Pennsylvania, he would spend time outdoors, climbing trees, after which he would develop severe general pustular psoriasis on his hands and all over his body, landing him in the hospital. While under medical care the boy was given aspirin which made his condition worse. To treat his condition, the doctors put the boy in a climate-controlled room to shield him from pollen. They also stopped giving him aspirin. As a result his condition improved. He was subsequently discharged after which he went to spend time in Ohio where he remained in good health. It’s only when he returned to Pennsylvania that the same thing happened – psoriasis returned and he was again hospitalised. At first, the doctors first concluded an aspirin allergy. After taking into account the fact that his reaction was only taking place in springtime in Pennsylvania when they have a very high number of birch trees, they correlated his condition with the natural salicylates in plants.

Again, studies linking psoriasis and salicylate sensitivity are sparse at best, so more information is required to evaluate whether a low salicylate diet is a beneficial treatment option for the condition.

Limitations

Due to the nature of the trials, most studies exploring dietary interventions and health outcomes will face some type of limitation of their findings. This does not mean said papers are unacceptable or invalid, it’s just the nature of dietary research – an imperfect process. Discussing limitations helps researchers understand the value and validity of a study and any challenges that were encountered. Science discoveries are usually the result of an iterative process, the undertaking of which relies on revealing the most accurate picture over time.

With that in mind, some of the limitations I identified while reading the studies in this article include sample sizes (many of the studies have less than 100 participants), lack of previous research studies on the topic, attrition and adherence to study requirements, uncertainty and conflicting results about salicylate content in foods, studies being non-blinded, subjective nature of self-reported data and confounding variables.

Again, while these limitations don’t necessarily negate any of the information presented, they do need to be considered in order to provide complete transparency.

What can you do to find out if salicylates may be contributing to your itchy skin?

If you have tried everything and still experience itchy skin in the form or urticaria, eczema and/or psoriasis it may be worth checking with your healthcare advisor whether you have a salicylate sensitivity.

The elimination diet is currently the only useful diagnostic tool healthcare professionals have in investigating salicylate sensitivity. The diet, developed by the Royal Prince Alfred Hospital (RPAH) involves cutting down on a range of food chemicals that are known to cause symptoms in some people. Due to its restrictive nature, the elimination diet should only be applied short-term so as not to starve the body of essential nutrients.

After being on the elimination diet for at least 3-6 weeks and once symptoms have settled for at least 5 days in a row, the next step is introduced, which involves identifying which particular food chemicals are tolerated by the individual, and which ones are not. This food challenge process involves testing each food chemical one by one, usually done by eating foods that provide a high dose of each particular chemical (e.g salicylates). If no symptoms are experienced during the period where the food chemical is introduced, it’s assumed that foods containing that chemical are safe to eat. However, if symptoms are experienced, then a food trigger is considered to have been successfully identified and it’s now a matter of discovering what an individual’s threshold is for that chemical.

Conclusion

The relationship between salicylates in diet and skin-related conditions is an ongoing debate among scientists. At present, mechanisms of the effect of salicylates on sensitivity reactions are largely unknown. What the above studies do highlight however is that low salicylate diets appear to provide positive effects on reducing self-reported symptoms in patients. It’s hoped with continued research into the topic, improved individualised treatments and guidelines will be obtained in order to help improve patient well-being.

 

References

(1) Loblay RH, Swain AR. ‘Food intolerance’. In Wahlqvist ML, Truswell AS, Recent Advances in Clinical Nutrition. London: John Libbey, 1986, pages 169-177.

(2) Zelickson BD, Muller SA. 1991. Generalized pustular psoriasis in childhood. Report of thirteen cases. J Am Acad Dermatol. 24(2 Pt 1):186–194. doi:10.1016/0190-9622(91)70025-w. http://dx.doi.org/10.1016/0190-9622(91)70025-w.

(3) Shelley WB. 1964. Birch pollen and aspirin psoriasis: A study in salicylate hypersensitivity. JAMA. 189(13). doi:10.1001/jama.1964.03070130005001. http://dx.doi.org/10.1001/jama.1964.03070130005001

(4) Swaine, A. R. “The role of natural salicylates in food intolerance.” Sydney Local Health District, 1988, https://www.slhd.nsw.gov.au/rpa/allergy/research/students/1988/AnneSwainPhDThesis.pdf. Accessed 11 January 2023.

(5) WARIN, R.P. (1960), The effect of aspirin in chronic urticaria. British Journal of Dermatology, 72: 350-351. https://doi.org/10.1111/j.1365-2133.1960.tb13817.x

(6) Sachdeva S, Gupta V, Amin SS, Tahseen M. Chronic urticaria. Indian J Dermatol. 2011 Nov;56(6):622-8. doi: 10.4103/0019-5154.91817. PMID: 22345759; PMCID: PMC3276885.

(7) Barrea L, Nappi F, Di Somma C, Savanelli MC, Falco A, Balato A, Balato N, Savastano S. Environmental Risk Factors in Psoriasis: The Point of View of the Nutritionist. Int J Environ Res Public Health. 2016 Jul 22;13(5):743. doi: 10.3390/ijerph13070743. PMID: 27455297; PMCID: PMC4962284.

(8) Kęszycka PK, Lange E, Gajewska D. Effectiveness of Personalized Low Salicylate Diet in the Management of Salicylates Hypersensitive Patients: Interventional Study. Nutrients. 2021; 13(3):991. https://doi.org/10.3390/nu13030991

(9) Cavkaytar, O, Arik Yilmaz, E, Buyuktiryaki, B, Sekerel, BE, Sackesen, C, Soyer, OU. Challenge-proven aspirin hypersensitivity in children with chronic spontaneous urticaria. Allergy 2015; 70: 153– 160.

(10) Taylor-Robinson DC, Williams H, Pearce A, Law C, Hope S. Do early-life exposures explain why more advantaged children get eczema? Findings from the U.K. Millennium Cohort Study. Br J Dermatol. 2016 Mar;174(3):569-78. doi: 10.1111/bjd.14310. Epub 2016 Feb 23. PMID: 26595368; PMCID: PMC4949701.

(11) French, S.A., Tangney, C.C., Crane, M.M. et al. Nutrition quality of food purchases varies by household income: the SHoPPER study. BMC Public Health 19, 231 (2019). https://doi.org/10.1186/s12889-019-6546-2

DISCLAIMER: This article is for informational purposes only. It is not intended to constitute or be a substitute for professional medical advice, diagnosis, or treatment. 

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