Drug Allergies
Chat Highlights
January 15, 2003

Norma Devine, Editor

On Wednesday, January 15, 2003, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Drug Allergies."

Moderator:  The topic tonight is glaucoma drug allergies.  Dr. Rick, which glaucoma medications cause the most allergies?  

Dr. Rick Wilson:  The order of the allergies that I see, starting with the most frequent, is:  (1) Iopidine, (2) Alphagan, (3) Propine, (4) Azopt, (5) Trusopt, (6) Timoptic/Betagan, (7) Ocupress, (8) pilocarpine.  The longer the patient is on the medication, the greater is the chance of an allergic reaction.

P:  Does a patient develop an allergy to the medications over time, or do  reactions start within a week of trying a new one? 

Dr. Rick Wilson:  With Epifrin, an older glaucoma medication, 50% of patients were allergic to it by five years.  So you could show no signs of allergy at four years and get it the next week.

Moderator:  How about the newer medications?

Dr. Rick Wilson:  Xalatan, Travatan, and Lumigan may be toxic to the cornea or conjunctiva, but the allergic rate is low, in my experience.  Red, irritated eyes are often seen without allergy.  For most eyedrops, allergies are usually in the 5 to 13% range.  

P:  Does an allergic reaction mean the drug is not lowering IOP (intraocular pressure)?

Dr. Rick Wilson:  No.  The drug can work very well and still cause an allergic reaction.

P:  Is episcleritis a sign of an allergy?

Dr. Rick Wilson:  No.  Episcleritis is just an inflammation of the superficial sclera.  It may be a sign of an autoimmune problem, or the cause may be unknown.   

P:  What is the difference between an allergy and a side effect?

Dr. Rick Wilson:  An allergy is a side effect,  as would be a change in iris color or shortness of breath.

P:  Do patients run out of options for medications because of allergic reactions or because the medications lose effectiveness?

Dr. Rick Wilson:  Allergy is usually more of an issue than loss of effect, although that can be seen as well.  Patients can also be allergic to the preservative in each of the drops, which is distinct from the medication itself and the vehicle which carries it (usually an artificial tear solution).  There are only a few kinds of preservative that are used in all kinds of drops.

P:  Could an allergy to eyedrops cause hives? 

Dr. Rick Wilson:  Yes, for sure.  Some internists discount (the possible allergic effect of) eyedrops because the volume is small. But the drops can go down the tear duct onto the nasal mucosa.  The mucosa is very vascular and absorbs almost all of the drug that hits it, so it is almost like injecting the medicine intravenously. 

P:  Does occluding the tear ducts avoid or delay developing an allergy to the drops?

Dr. Rick Wilson:  No, but it markedly decreases the amount of the drug that hits the body.

P:  The last few days I have had a bad case of hives.  Is it possible that I could be allergic to my eye drops?  I use Travatan and Alphagan.

Dr. Rick Wilson:  Unusual, but possible.  Occasionally, we see a rash from Trusopt or Azopt.

P:  What does an allergic reaction look like?  Red eyes? 

Dr. Rick Wilson:  Usually the blood vessels on the white of the eye are dilated, giving the eye a red, occasionally watery, look with tiny bumps lining the lids.  The lids may also be red, swollen, and scaly if the allergy is chronic.

P:  Would this explain "itchy" eyes?

Dr. Rick Wilson:  That could be an environmental allergy or a medicinal allergy.  Itching is usually caused by an allergy.

P:  I get headaches with Travatan.  Is that an allergic reaction?

Dr. Rick Wilson:  Headaches are not usually due to allergy.  Travatan is usually metabolized in the blood stream very quickly, so systemic side effects are rare, but possible.

P:  Does an allergy to one medication increase the possibility of being allergic to other medications?

Dr. Rick Wilson:  Yes.

P:  Can an allergic reaction to drops ever create a chain reaction that eventually damages the optic nerve or retina?

Dr. Rick Wilson:  An allergic reaction to lens material that is liberated in the eye is called phacoanaphylaxis and is a very dangerous and damaging reaction.  However, the reaction is to an antigen inside the eye, not one dropped onto the outside of the eye.

P:  Is there a danger in ignoring an allergic reaction and continuing to use the medication? 

Dr. Rick Wilson:  Yes.  The allergy causes changes in the conjunctiva, or top layer of the eye, that are long-standing and decrease the success of a surgical procedure for glaucoma, if surgery is performed. It may also cause a dry eye and conjunctival scarring.

P:  Are medications available to counteract the reactions?

Dr. Rick Wilson:  They can suppress the reaction, but not counteract it.

P:  Since other allergies, such as hay fever,  can affect the eyes, how do you determine the cause of the reaction?

Dr. Rick Wilson:  Usually there will be a time relationship between the allergen and the itching.  So I ask my patients to keep track of what they have come in contact with just before their eyes start to itch.

P:  Is there such a thing as an acute allergy to the drugs?

Dr. Rick Wilson:  Yes, if you have been sensitized to the drug before,  developed an allergy to it, and then were later exposed to it again, the reaction will usually begin much more rapidly.

P:  I use Alphagan P, and now and then develop a rash on my neck.  Is this one of the known allergic reactions to Alphagan P? 

Dr. Rick Wilson:  It is possible.  I would try closing my tear duct to reduce the amount of medicine getting into the body, and see if that has any effect on the rash.

P:  I had serious, unrecognized systemic problems with timolol for many years.  Even after that bad experience years ago, recently I was very slow to suspect that Azopt might be the cause of a continuing allergy.  The symptoms were rhinitis, sporadic facial hives, and quasi-chills.  I felt bad, too, fighting off sinus infections all of the time.  Dr. Weitzman said it was a sulfa sensitivity.  Do you think it could have been the preservative?  No other drop has ever caused that trouble.

Dr. Rick Wilson:  No, I think it was most probably the Azopt. Preservatives usually cause a local allergy, and not systemic side effects.

P:  Are some drops irritating in the beginning and then the eyes tolerate the drop? 

Dr. Rick Wilson:  Yes, Trusopt is a good example of that.  Lumigan is the granddaddy of the starting red eye that often improves over the first two weeks.

P:  So intense stinging doesn't necessarily denote an allergy?

Dr. Rick Wilson:  No, it is not an allergy.  The usual cause is a dry eye that leaves little bare spots on the front of the cornea.  Most drops are usually slightly acidic, compared to tears, to improve the shelf life of the medication.  When the acidic solution hits those bare spots on the cornea, it can really burn.

P:  Is the dry eye that develops when using glaucoma drops considered an allergic reaction to the medication?

Dr. Rick Wilson:  It can be an allergic or toxic reaction.

P:  I had a fiercely bad reaction to prednisone, which I was once given for a back problem.  At the hospital where I was taken, I was told I was allergic to the drug and should not take it again.  If I ever need steroid treatment for my eyes, what would my options be?

Dr. Rick Wilson:  I would try non-steroidal medication first.  Drugs like Motrin are available as drops.  It is unlikely you were really allergic to prednisone, since prednisone is a synthetic form of a hormone in the body.  However, higher doses of prednisone can cause bad systemic side effects.  

P:  I was diagnosed with early-stage, normal-tension glaucoma in December last year.  My visual field test was normal.  I take Clarinex for allergies, as needed.  Does Alphagan P have any adverse drug reaction with Clarinex?

Dr. Rick Wilson:  Usually not.  I've never seen it.

P:  How effective are mast cell stabilizers (sodium chromoglycate, etc.) in treating allergy to other drops?

Dr. Rick Wilson:  They help, but can't make up for the chronic allergic stimulation.

P:  You said that the eyelids may be red, swollen and scaly if the allergy is chronic; if the allergy is acute, the patient would have a rapid reaction to the medication if it is reintroduced at a later time.  I don't understand, then, the effect of a chronic reaction.  I developed swollen red eyelids and very red eyes when using Alphagan.  What does that chronic reaction mean to me (as opposed to an acute reaction)?

Dr. Rick Wilson:  The scaling takes more time to develop than just the red swollen lid. 

P:  After about six weeks of using glaucoma eyedrops, is it normal for side effects, such as irritation, to increase? 

Dr. Rick Wilson:  I would not want to say that side effects are normal.  Some side effects, like the redness caused by Lumigan, often improve with time.  Others get worse.

P:  My two-year-old child was on Cosopt, then went to Timoptic and is now back on Cosopt.  I give it to her at night, right after I take her aphakic contacts out, but she cries and says it burns.  I tried to give it to her in the morning, but the Cosopt seemed to make her very moody and cranky.  Is there a best time to give the Cosopt, four times a day? I heard the morning is best, because pressure is highest in the morning.  Is there anything I can do to decrease the irritation?

Dr. Rick Wilson:  You are most likely right on both issues.  If the Cosopt burns, I would change to Timoptic XE and Azopt.  The Timoptic should be once a day; the Azopt twice.  Cosopt contains both Timoptic and Trusopt.  Azopt is a similar drop to Trusopt, but causes less burning when instilled in irritated eyes, such as those with contacts.

P:  Dr. Wilson, before  you leave I want to tell you that you have helped me understand my new diagnosis better after reading the chat highlights. Thank you so much!

Dr. Rick Wilson:  My pleasure. That's what makes missing time from my family worthwhile.  Have a good week, everyone.

End of highlights for January 15, 2003.

On January 22, Dr. Wilson discussed "Blood Flow to the Eye" in the Chat room. Click here for highlights of that meeting.

Click here for the most recent glaucoma chat highlights and links to the chat archives.

Click here for upcoming glaucoma chat events.