Among the many psoriasis triggers, medications and climatic influences play an important role in inducing new psoriasis plaques.
Medications as Psoriasis Triggers
Many drugs are known either to precipitate or to exacerbate psoriasis and thus act as psoriasis triggers. Rather than being simple drug reactions, these observations throw some light on the causes of psoriasis.
A number of beta-adrenoreceptor blocking drugs propranolol, practolol, metaprolol and oxyprenolol- used to treat hypertension and heart disease have been reported to induce a papulo-squamous eruption that resemble psoriasis.
The cyclic AMP(cAMP) level in psoriatic epidermis is decreased and this decrease may induce accelerated turn over of epidermal cells. Beta blockers further reduce cAMP levels and thereby exacerbate psoriasis. The lesions produced by these drugs are less scaly and less erythematous. The palms, soles and elbows are only rarely involved, and the eruption usually subsides within 2 to 6 weeks of cessation of beta-blocker therapy.
Non-steroidal anti-inflammatory drugs, indomethacin, salicylates, diclofenac, phenylbutazone, oxyphenbutazone and ibuprofen have been reported to either precipitate or exacerbate psoriasis.
Treatment of depression with lithium compounds in psoriasis patients can destabilize and exacerbate the psoriasis.
Precipitation of generalized pustular psoriasis in patients with stable psoriasis vulgaris has also been reported following lithium treatment for manic-depressive psychosis.
Lithium compounds have an inhibitory effect on adenyl cyclase and reduce hormone induced accumulation of cAMP in vitro. This may be the mechanism of exacerbation of psoriasis in these patients.
Trazodone, another new antidepressive drug which is a serotonin antagonist, can also cause generalized pustular psoriasis. This suggests that an alternate mechanism may also be involved.
Too rapid a withdrawal of corticosteroid therapy in patients with psoriasis may result in precipitation of generalized pustular psoriasis or may cause exfoliative erythroderma as a rebound phenomenon. Occasionally, topical corticosteroids, especially the more potent ones, also cause such exacerbations.
Chloroquine is another drug that has been known to exacerbate psoriasis, often leading to exfoliative erythroderma, although its exact mechanism in causing such an exacerbation not fully understood.
Other drugs rarely reported to exacerbate psoriasis are clonidine, a centrally acting alpha adrenergic agent with independent peripheral effects, glibenclamide and tetracycline.
Climate as a Psoriasis Trigger
Farber and Nall found that 89% of patients in their study experienced worsening of their psoriasis during winter.
High humidity is beneficial, so is gradual tanning sunlight. Harsh sunlight, though, may worsen psoriasis by inducing the Koebner phenomenon through sunburns. Zlotogorski observed that many male patients who drove cars had less involvement of the left elbow than the right one because the left arm was exposed to sunlight through the window.
Winter tends to be the most challenging season for people living with psoriasis. Numerous studies indicate cold weather is a common trigger for many people and that hot and sunny climates appear to clear the skin.
Cold winter weather is dry, and makes the skin drier. This usually worsens psoriasis. Psoriasis can become even more severe when the stress of the holidays and winter illnesses combine to compromise immune systems.
While hot and sunny may help clear psoriasis, air-conditioning can dry out the skin and aggravate psoriasis. Regular moisturizing and a little humidification of the interiors can help prevent this.
Next: Smoking and Alcohol as Psoriasis Triggers
Reference
Psoriasis, in Rook’s Textbook of Dermatology, 7th Edition, 2004
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