The following was taken from the Pharmacists Desk Reference

The pharmacist is in a unique position to counsel tanning consumers on both prescription and non-prescription medications, herbal and other "natural" products and perhaps even cosmetics, shampoos and similar purchases that may make people sensitive to ultraviolet light. This is also known as photosensitivity. Many medications and topical products can cause photosensitive reactions or increase a person's risk of developing sunburn. This chapter will describe photosensitive reactions, discuss what people are most at risk, and list the medications, common herbal products and topical agents most likely to cause these reactions.

What is a drug-induced photosensitivity reaction?

A drug-induced photosensitive reaction most commonly appears as an exaggerated sunburn. It occurs when a person takes certain medications or applies, either intentionally or unintentionally, offending substances to the skin and is exposed to ultraviolet radiation. A photosensitive reaction should be considered in people experiencing sunburn of greater severity than would normally be expected for them, or who develop rashes in areas exposed to the sun or tanning unit.

How common are drug-induced photosensitive reactions?

Drug-induced photosensitive reactions are not uncommon, and are actually increasing in frequency with the increased emphasis on health that includes outdoor exercise during both the summer and winter, and, because sunbathing and the use of tanning salons continue to be popular. People are living longer and are likely to retire to sunny climates, which usually increases exposure to the ultraviolet light; older "seasoned citizens" also tend to take more medications, many of which may be implicated in drug-induced photosensitive reactions. The use of herbal and other "natural" products is also increasing, and people may not be aware that some of these can also cause photosensitive reactions. Photosensitive chemicals are widely used in medications, cosmetics, lotions, shampoos, hair dyes, soaps and other topical products.

Who experiences drug-induced photosensitive reactions?

As discussed above, drug-induced photosensitive reactions are quite common and can occur in virtually anyone, though to widely varying degrees of severity. People with fair complexions; red, blonde or light brown hair; blue or green eyes; and who generally sunburn easily and do not tan are most at risk. A history of severe sunburn(s) may also increase the risk, as may a history of allergies, especially contact hypersensitivities, to cosmetics or other topical agents. The frequency, type and amount of UVR the person is likely to receive should also be considered. For example, a person who receives only casual exposure to sunlight outside its most intense hours of 10 a.m to 3 p.m. would be less likely to have a reaction than would someone who routinely sunbathes or visits a tanning salon.

Are all drug-induced photosensitive reactions the same?

Drug-induced photosensitive reactions, which include reactions caused by medications, herbal products or other agents either intentionally or unintentionally applied to the skin, can be divided into two types, phototoxic and photoallergic reactions. The same medication or agent may produce both phototoxic and photoallergic reactions, and it can sometimes be difficult to differentiate between the two types of reactions clinically.

By far, the most common type of induced photosensitive reaction is the phototoxic type, where the offending substance is thought to act as a chromophore, absorbing ultraviolet radiation. When the chromophore reaches a sufficient concentration in or on the skin, and when the skin is exposed to the appropriate wavelength of ultraviolet radiation, energy is emitted which damages the adjacent tissue to cause a phototoxic reaction. The wavelength of radiation necessary to produce such a reaction depends on the absorption spectrum of the offending substance.

Phototoxic Reactions are dose-dependent, and will occur in almost any one who takes or applies an adequate amount of the offending substance. The dose necessary to produce such a reaction varies from person to person, and will depend upon such factors as complexion, hair and eye color, usual ability to tan (skin type) and the amount of ultraviolet radiation exposure. Phototoxic photosensitive reactions are not allergic reactions and can occur on first exposure to the substance.

A phototoxic reaction usually has a rapid onset (within several hours after exposure to ultraviolet radiation) and presents as an exaggerated or intensified sunburn with erythema (redness), pain and prickling or burning. Blistering, peeling and abnormally increased coloration of the skin may occur in severe cases. Symptoms usually peak 24 to 48 hours after initial exposure and are usually limited to the areas of the skin exposed to ultraviolet radiation.

In Photoallergic Reactions, the offending substance is altered in the presence of ultraviolet radiation to become antigenic and can act as a toxin. These reactions are less common and involve antigen-antibody or immune-mediated reactions. Photoallergic reactions do not occur on first exposure to the medication, but like other allergic reactions, they require prior or prolonged exposure (sensitization period) to the offending substance. Once sensitization has occurred, subsequent exposure to even small amounts of the offending substance will produce a photoallergic reaction.

Photoallergic reactions are not dose-related. They probably represent a type of delayed hypersensitivity reaction, and since time is needed for the body to mount an immune response, the onset of a photoallergic reaction is usually delayed for 24 hours or even several days. Recovery is also often slower than from a phototoxic reaction, with the reaction sometimes persisting for some time after the offending substance has been discontinued.

These reactions may appear as warmth and swelling, noncontagious inflammation of the skin, characterized mostly by redness, itching, and the outbreak of lesions that may discharge matter and become encrusted and scaly.

Photoallergic reactions may also be small, flat lesions which differ in color from the surrounding skin, large blisters, usually 2 cm or more In diameter. Severe hives and lesions may also develop within minutes after exposure to ultraviolet radiation. In small percentage of cases, sensitivity to light may continue even after the offending substance is discontinued.

Photoallergic reactions primarily occur on the areas of the skin that are exposed to ultraviolet radiation, but may extend beyond these to other areas. They are more common in adults than children, possibly because adults have usually been exposed to more medications and topical agents. Photoallergic reactions are more often caused by topical agents, but may also occur with systemically administered medications.

Which medications are most likely to cause photosensitivity?

Many medications and some herbal and other "natural" products have been reported to cause photosensitive reactions. In addition to topically-applied medications, cosmetics, foods and other chemicals may also produce photosensitive reactions, as may agents unintentionally applied to the skin (by handling plants, exposure to airborne allergens or wearing certain types of jewelry or leather). Some ingredients in cosmetics, perfumes, colognes, after-shaves, soaps, deodorants, lotions, shampoos, hair sprays, hair dyes, contact lens solutions and even sunscreens may also cause reactions.

Not only are the properties of the medication important, but the consumers most likely to use such products must also be considered. For example, oral contraceptives and similar hormones are commonly used by people likely to sunbathe and use tanning salons, so counseling these clients on drug-induced photosensitive reactions is especially important.

How are photosensitivity reactions diagnosed?

Although indoor tanning salon operators aren't typically qualified to diagnose disorders, a photosensitive reaction should be considered in any client experiencing sunburn of greater severity than would normally be expected for them, or developing a rash in areas exposed to the sun or tanning unit. A trained clinician will typically diagnose based on the person's history and clinical presentation. All prescription and non-prescription medications, herbal and other "natural" products, topical agents, cosmetics, perfumes, colognes, after-shaves, soaps, deodorants, lotions, shampoos, hair sprays, hair dyes, sunscreens and similar products, particularly new ones, would most likely be reviewed. Work, hobbies and other sources of unusual chemical exposures may also be considered.

How can photosensitivity reactions be prevented or minimized?

Tanning should be avoided while taking medications that commonly cause photosensitive reactions. Since some medications remain in the body for significant periods of time after discontinuation, consumers should also be careful for a few days after suspected medications are discontinued. If a person insists on spending significant time in the sun or indoor tanning, an alternate medication should be considered, if possible and under a doctor's care.

How should photosensitivity reactions be treated?

Like sunburn, photosensitive reactions are better prevented than treated. Most photosensitive reactions can be treated the same as an ordinary sunburn, with cool wet dressings, emollients or cool baths. Oral analgesics may be helpful. Topical anesthetics should be avoided, or at least used sparingly (perhaps only at bedtime), since they may cause contact sensitization and photosensitive reactions.

Under a doctor's care, topical corticosteroids, such as hydrocortisone, may be helpful; topical or systemic antipruritic agents may be useful in some cases, and oral diphenhydramine taken at bedtime may help the person sleep. If they experiences fever, chills, nausea, vomiting or prostration (exhaustion), a healthcare provider should be consulted. Systemic corticosteroids, such as prednisone, may be necessary to treat severe reactions.

When possible, the offending medication or other agent should be discontinued. This usually results in regression of the reaction, though this may be slow. A person experiencing a photosensitive reaction should also be careful to avoid further significant exposure to the sun and should avoid ultraviolet light, at least until the photosensitive reaction subsides and the offending substance has been stopped. Approximately 10 percent to 20 percent of people may have persistent photosensitivity for prolonged periods of time. As indoor tanning professionals, it is important that you advise your clients to seek medical attention if symptoms are severe.

The most common photosensitizing materials are listed on the following pages. This is not a list of every material that could have photosensitizing effects. Again, if there is any question about a drug or product that a client uses, have that person consult a physician or pharmacist. Remember, it is always best to error on the side of safety.

Before using the list, remember the following:

1.      NOT all individuals who use or take these medications will experience a photosensitive reaction. Also, an individual who experiences a photosensitive reaction on one occasion will NOT necessarily experience it again or every time.

2. A medication will NOT cause the same degree of skin reaction in all individuals.Brand names of products should be considered only as examples; they do NOT represent all names under which the generic product may be sold.

Jerome I. Levine, M.S., R.Ph., prepared the following list for the Federal Drug Administration. The list was published under the title "Medications That Increase Sensitivity To Light: A 1990 Listing." The FDA has confirmed this list to be the most recent.

The mention of commercial products, their sources, or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products by the Department of Health and Human Services.

Reported Photosensitizing Medications

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