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Your lenses sat comfortably for years — and suddenly your eyes burn, your vision blurs in the afternoon, or your soft lenses have an orange tinge. Quite often a new medicine is behind it. Some active substances reduce tear production, others colour the tear fluid, and preservatives in eye drops build up in soft lenses. This guide shows you which medicines are typically behind it, how to combine eye drops and lenses correctly — and when the lenses have to come out straight away.
brite records what you have been taking and since when — so you spot the connection faster. Free of charge.
A contact lens floats on the tear film (the thin layer of fluid on the surface of the eye). This film consists of three components: a watery layer from the lacrimal gland, a mucous layer that makes it stick to the cornea, and a thin oily layer from the meibomian glands on the edge of the eyelid, which slows evaporation. The lens splits this film into one layer in front of the lens and one behind it — and in doing so makes it less stable.
Anyone who wears contact lenses therefore has fewer reserves. Even a slight reduction in the amount of tears or a change in the oily layer is enough for the lens to rub, dry out faster and collect deposits. Accordingly, many contact lens wearers — especially those with soft lenses — develop dry eyes in the long run.¹ Typical signs are:
These symptoms have many possible causes: screen work, dry air from central heating, poorly fitted lenses, age, hormonal changes. An overview of all the triggers can be found in the article Dry eyes. Here the focus is on one specific question: what part do your medicines play?
A whole range of active substances can affect the tear film — the international Tear Film & Ocular Surface Society (TFOS) has summarised the connections in a report of its own.² The most important groups in everyday life:
| Drug group | Examples | How they act |
|---|---|---|
| Antihistamines (allergy medicines) | Cetirizine, loratadine, older sleep and travel-sickness remedies | Dampen tear secretion; older, more strongly sedating substances usually do so more markedly |
| Tricyclic antidepressants | Amitriptyline | Anticholinergic effect: fewer tears and less saliva |
| Other antidepressants and sedatives | SSRIs, benzodiazepines | Are also associated with dry eyes |
| Medicines for an overactive bladder | Oxybutynin, solifenacin | Anticholinergic: a dry mouth and dry eyes are among the typical side effects |
| Beta blockers | Metoprolol, timolol eye drops | Can reduce tear production — also as eye drops for glaucoma |
| Diuretics (water tablets) | Hydrochlorothiazide | Can reduce the watery layer of the tears |
| Retinoids (vitamin A derivatives) | Isotretinoin | Impair the meibomian glands and thus the oily layer |
| Hormone therapies | Oestrogens, anti-androgens | Affect the lacrimal gland and the eyelid-margin glands; the evidence is inconsistent |
Two honest caveats: not everyone who takes one of these medicines gets dry eyes — many notice nothing at all. And often several small effects add up, for example an allergy medicine in spring, plus a bladder medicine and the dry office air. Especially with several active substances that have an anticholinergic effect, it is worth looking at the medication as a whole.
Isotretinoin, which is used for severe acne, deserves a section of its own. The active substance shrinks the sebaceous glands of the skin — and in doing so also acts on the meibomian glands on the eyelid margin. The oily layer of the tear film becomes thinner and the tears evaporate faster. Dry eyes are therefore among the very common side effects, and the summary of product characteristics (Fachinformation) explicitly points out that contact lenses may be less well tolerated during treatment.³
The symptoms usually resolve once treatment has ended. Anyone who already had problems with dry eyes before treatment should discuss this with the prescribing practice before starting.
Soft contact lenses consist largely of water and absorb substances from the tear fluid — dyes included. Some medicines colour body fluids and therefore the tears as well. The result is lenses with a yellowish, orange or reddish tinge that often can no longer be cleaned out.
| Active substance | Used for | Discolouration | What to do |
|---|---|---|---|
| Rifampicin | Tuberculosis and certain other bacterial infections | Reddish-orange discolouration of urine, sweat and tears; soft lenses can be permanently discoloured | Avoid soft lenses for the duration of treatment, or use daily disposables after consultation |
| Sulfasalazine | Ulcerative colitis, rheumatoid arthritis | Yellow-orange discolouration of the skin and body fluids; soft lenses can be permanently discoloured | Talk to your eye specialist or contact lens optician about the type of lens and wearing time |
| Preserved eye drops (benzalkonium chloride) | Many multi-dose eye drops | Can discolour soft lenses and build up in them | Take the lenses out before using the drops and wait at least 15 minutes |
| Fluorescein | Dye used during examinations at the ophthalmology practice | Stains soft lenses yellow-green | Take the lenses out beforehand; the practice will tell you when you can put them back in |
For rifampicin and sulfasalazine, the warning about discoloured contact lenses is stated explicitly in the summaries of product characteristics.⁴ The discolouration itself is usually harmless and a known effect — it is not a sign that the medicine is not being tolerated. It is annoying all the same, especially with expensive monthly or yearly lenses. So whenever you get a new medicine, ask at the pharmacy whether it can colour body fluids. Rigid gas-permeable (hard) lenses absorb dyes much less than soft ones.
In the digital medication plan in brite you can see all your active substances at a glance — for the appointment at the ophthalmology practice too.
Many eye drops in multi-dose bottles contain a preservative, usually benzalkonium chloride. It keeps the bottle free of germs after opening, but it can be absorbed by soft lenses, build up in them, discolour the lens and irritate the surface of the cornea. The Europe-wide standard labelling for this excipient therefore reads: remove contact lenses before use and put them back in no sooner than 15 minutes later.⁵
Even with preservative-free drops: not every product is intended to be dropped onto the lens. Only products explicitly labelled as “suitable for contact lens wearers” or “for use with contact lenses” may be used while the lens is in.
In glaucoma, eye drops are often a lifelong treatment — once or several times a day. Many of these products are preserved, and some active substances, such as beta-blocker drops, can themselves reduce tear production. Wearing lenses is nevertheless often possible if the dropping times are well planned: drops in the morning before putting the lenses in and in the evening after taking them out. Whether a preservative-free product makes sense is decided by the treating ophthalmology practice.
In the pollen season the eyes itch and water, the lens collects pollen, and antihistamine eye drops are added on top. Many people affected cope better with daily disposable lenses during this time, because deposits do not accumulate over weeks. On particularly bad days, glasses are the gentler choice. Background on treatment can be found in the article Allergic rhinitis.
With conjunctivitis or while using antibiotic eye drops, the rule is: no lenses until it has healed. Lenses that were worn and the case should as a rule be replaced afterwards to avoid reinfection. Eye drops containing cortisone belong exclusively in the hands of an eye specialist — they can raise the pressure inside the eye and mask infections.
Moisturising eye drops (artificial tears) are the first step against dry eyes. For lens wearers, three criteria count:
To be honest: artificial tears relieve symptoms but do not cure anything. How well they help varies greatly from person to person, and it often takes a little trial and error. If you need them several times a day and the symptoms persist anyway, that is a reason for an examination by an eye specialist — not for more and more drops.¹
Simple measures help alongside: blink consciously and take screen breaks, drink enough, humidify heated air and, if the eyelid margins are affected, carry out regular lid hygiene with warm compresses — as instructed by your eye specialist.
Dry eyes are usually harmless. An irritated cornea under a contact lens is, however, more susceptible to inflammation — and an inflammation of the cornea (keratitis) can permanently endanger your sight.
Symptoms that begin after a new prescription should also be raised, even if they are not dramatic. An overview of which medicines can damage the eye itself — for example the lens, the optic nerve or the retina — is given in the guide Medications and the eyes.
The brite medication reminder plans your dropping times around putting your lenses in and taking them out.
Take a complete list of your medicines with you to the appointment at the ophthalmology practice — including over-the-counter allergy medicines, sleep aids and food supplements. Many connections only become apparent once all the active substances are on the table.
With age, tear production decreases anyway, and the number of medicines rises. Several active substances with a mild drying effect can add up. Anyone who regularly takes five or more medicines can have their overall medication checked as part of a medication review at the pharmacy.
Hormonal changes alter the surface of the eye — many women first notice during the menopause that their lenses no longer sit as comfortably. Whether hormone therapy tends to improve or worsen this has not been clearly established.
With long-standing diabetes, the sensitivity of the cornea can decrease. The treacherous part: irritation and small injuries are noticed later. Regular check-ups with an eye specialist are particularly important here — quite apart from the lenses.
During pregnancy, too, the tear film and cornea change, and lenses are sometimes temporarily less well tolerated. Which eye drops are suitable then is something you clarify with your practice; general advice is given in the guide Medications during pregnancy.
Medication plan
All your active substances — including eye drops and over-the-counter allergy medicines — in one place, ready for your appointment at the ophthalmology practice.
Medication reminder
Plans dropping times to fit in with your lens routine — in the morning before putting them in, in the evening after taking them out.
Interaction check
Shows you when several drying active substances add up in your medication — a good reason for a conversation at your practice.
Health history
Documents since when your eyes have been burning and how long you can tolerate your lenses — so the connection with a new medicine becomes visible.
