9 Common Medications That Turn The Hawaii Sun Against You – Millions Of Visitors Take Them Daily

Nearly 10 million people flew to Hawaii last year.

A lot of them packed a pill that quietly makes our sun worse. I’ve lived on Oahu for over thirty years, and I’ve watched good people cook on day one for reasons they never saw coming.

It’s not the sunscreen. It’s the prescription.

Nine of them do this, and number nine doesn’t even need a prescription. Here’s why our sun is the wrong place to find out.

Start Here If You Read Nothing Else

Some everyday medications make your skin soak up sunlight. 💊 Doctors call it photosensitivity. You’d call it the worst burn of your life on a Tuesday.

More than 300 medications are documented sun-sensitizers. A Dutch case-control study found over 40% of the population takes at least one.

So this isn’t a rare thing that happens to unlucky people. It’s a normal thing that happens to normal people, in the wrong place.

The wrong place is here. And the reactions split into two kinds, which matters more than you’d think, because they don’t look the same and they don’t show up on the same day.

Most of them are phototoxic. That means the drug drinks in the light and damages the cell directly. It hits within minutes to hours. It looks like a sunburn that went insane.

The rest are photoallergic. Your immune system gets involved. That one waits 24 to 72 hours, then shows up as an itchy, eczema-like rash that can spread to skin the sun never touched.

Dr. Anthony Fernandez, a dermatologist at Cleveland Clinic, put it plainly last year. The reaction, he said, “can present as exaggerated sunburn or as eczema-like red, itchy spots.”

Two different animals. One cause.

So why does a mild risk on the mainland turn ugly the second you land? That part’s about geography.

Why Our Sun Is Not Your Sun

Our sun is a different sun. That’s the part I can’t get visitors to believe until it’s too late.

We sit around 20 degrees north. No other state is closer to the equator. The light comes down steeper, through less air.

The EPA rates summer midday UV here at 11 to 12, which is the top of their scale, the band where they say bare skin burns in minutes.

Winter doesn’t save you either. Midday still runs 6 to 8.

Now the number that stops me every time I read it.

The American Cancer Society found that 97% of Hawaii’s melanoma cases trace back to UV. Highest share in the country.

UV-attributable melanoma among white residents here runs 65.1 per 100,000. Also the highest in the country, by a wide margin over second place.

Read that again. Ninety-seven percent. Almost none of it is bad luck.

Here’s what makes it sneaky. The trade winds pull the heat right off your skin, so the alarm that tells you you’re cooking never rings.

The water sits in the high 70s, comfortable enough to float in for two hours. And while you float, roughly 40% of the burning rays are still reaching half a meter down.

Your back is getting it twice, once from the sky and once bounced off the surface.

Let me kill the myth that costs people the most. 🌥️ Clouds do not protect you here. Up to 80% of UV comes straight through light cloud.

Worse, our puffy trade-wind clouds can bounce extra UV off their edges and push levels higher than a clear blue sky.

A partly cloudy day here can burn you harder than a bright one. That one still bothers me, because it’s the day everybody skips the sunscreen.

And it almost always happens on day one, which is why the first 24 hours in Hawaii are worth planning down to the hour instead of winging it off the plane.

Now let’s go through the nine.

The Nine Pills Worst Offenders First

I’m ranking these by how likely you are to be carrying one, not by how exotic they are. Read it against your own pill organizer.

The Blood Pressure Pill Millions Take Without Thinking

Hydrochlorothiazide goes first because so many people take it.

Around 38 million prescriptions a year in the US.

It’s the water pill in a huge share of blood pressure combos, and plenty of folks couldn’t tell you they’re on it, because it’s baked into a two-drug tablet with a different name on the bottle. 🩺

The Danish data on this one is hard to shake off. Researchers looked at more than 80,000 skin cancers against roughly 1.6 million controls.

Almost four times the odds of squamous cell skin cancer for heavy long-term users. The highest-dose group hit more than seven times.

The FDA updated the label in 2020. Europe’s regulator did the same in 2018.

Now the honest part, because this scares people into doing something dumb. That risk is cumulative, built over years of daily use.

It is not a “you’ll burn on Waikiki this afternoon” risk. Nobody should stop a blood pressure pill for a vacation. That trade is a terrible one.

Hydrochlorothiazide is also the odd one out in a way that matters later, and I’ll come back to it.

The Antibiotic That Burns Your Hands First

Doxycycline is the one I’d bet money on. People take it for acne, for Lyme disease, and as a malaria pill. Under strong sun, it’s vicious.

My friend Dave flew in from Ohio for a week, on doxycycline for adult acne. Nobody at his pharmacy mentioned the sun. He’d read the sticker the way we all read stickers, which is to say not at all.

Day two, we did Hanauma Bay.

He wore a rash guard, so his back and shoulders were fine. But he floated face-down over the reef for almost two hours with his hands out in front of him, the way everybody does. 🤙

By dinner his knuckles were swollen, red, and hot enough to feel from an inch away. He couldn’t hold a fork.

“It feels like they’re burning from the inside,” he kept saying, and he wasn’t being dramatic.

He ate rice with a spoon in his fist like a toddler. That was the trip he’d saved two years for.

That’s the classic doxy pattern. Hands, forearms, the back of the neck. The exposed edges, right where the sunscreen wore off first.

Here’s where I’ll break with a lot of what you’ll read.

You’ll see confident percentages quoted everywhere, that 3% of users react at one dose and 42% at another. When researchers went looking specifically at how often this happens, they concluded the evidence base wasn’t good enough to give a number.

So the dose-dependence is real. The tidy percentages are not.

I’d rather tell you it’s unquantified than hand you a fake number, because the fake number is what makes people gamble.

What I can tell you is where Dave’s burn actually started. And it wasn’t the bay.

Why The Burn Starts Before You Reach The Beach

This is the part that reframes everything above, and almost nobody tells visitors.

Nearly all drug photosensitivity is driven by UVA, the long wavelengths. Not UVB, the ones that give you a normal sunburn.

That distinction sounds like trivia until you learn what glass does.

Window glass blocks essentially all UVB. Under 1% gets through. It does almost nothing about UVA.

Ordinary glass lets roughly 63% to 74% of UVA sail right through.

Sit with that for a second. Glass blocks the rays that make you feel burned, and passes the rays your pills react to. You get the damage without the warning.

A 2022 review in Frontiers in Allergy says it outright: because these reactions depend on UVA, they “may be induced also through window panes at any time of the year.”

Cars Make It Concrete

Windshields are laminated, with a plastic layer that soaks up UVA, and they block 96% to 99% of it.

Side windows are tempered glass, no layer, and they don’t.

One study of 29 cars found side windows blocked an average of 71%, ranging from 44% to 96%. A newer 2025 study of 34 cars found side glass averaging around 89%.

Better. Still a lottery, and you cannot tell which car you’re in by looking at it.

British researchers put a number on it that I’ve never forgotten.

Through clear glass, 30 minutes gets you a reaction-triggering UVA dose. Through good laminated grey glass, the same dose takes 50 hours.

Same sun. Same drive. Two completely different afternoons.

Dave’s hands were on my dashboard from the airport. He started on the H-1 and finished on the reef.

The Myth I Want To Bury

You’ve heard that drivers get more skin cancer on their left side from the window.

The left-side excess is real, but it’s small, about 1.1 times.

And a study of roughly 100,000 melanoma cases across six countries found the same left-sided excess in England, Scotland, and Australia, where everyone drives on the other side.

The driving explanation does not survive its own data. The glass matters. The steering wheel story is mostly folklore.

So what do you actually do?

The decision gets made before you land, which is one of the ten things worth sorting out before your plane touches down, right alongside the rest of the getting-around stuff most people improvise badly.

Get the sunscreen on in the rental lot, not at the beach. That drive from HNL to the North Shore is 90 minutes of side-window UVA.

Pro tip you can act on today. 🚗 Skip the convertible if you’re on any of these nine.

It’s the one hard number that exists: with the top down, you take 62% of the ambient UV dose, measured.

It’s also the pricier rental. When I priced a summer day out of Honolulu with Discount Hawaii Car Rental, a Mustang convertible ran about $116 all-in against roughly $99 for an economy car.

You’re paying a 20% premium to delete your own roof. (That’s one snapshot, one date, so treat it as a shape, not a quote.)

And one bit of local trivia worth knowing. Hawaii law caps front side windows at 35% VLT, but that limit is about visible light, not UV.

Clear UV-blocking film runs around 90% VLT and is perfectly legal here. Locals who drive for a living get it installed.

You can’t put it on a rental, which is exactly why visitors eat the exposure that residents quietly opted out of years ago.

Remember hydrochlorothiazide being the odd one out? It’s the one drug in this group with documented UVB-triggered reactions.

Meaning the car is the one place it’s less of a problem. Small mercy. Take it.

Back to the list, because seven more can still get you.

Seven More That Catch People Every Summer

The Sulfa Antibiotic That Clears Fast

Bactrim shows up for UTIs and skin infections. Only half of it causes trouble, the sulfamethoxazole part, and it’s phototoxic.

It behaves like an exaggerated sunburn, not an allergy.

The good news is real. Bactrim clears your system in about three days.

So if your doctor has any flexibility on timing, finishing the course before the trip is a genuine option. Ask. The worst they’ll say is no.

One thing I won’t skip. I’ve read a story from someone who took Bactrim at twelve and said “it felt like my skin was burning from the inside out.”

She was later diagnosed with lupus.

Sometimes a wild sun reaction isn’t only the drug talking. Don’t wave it off as bad luck.

The Strong Antibiotics You Might Be On Right Now

Cipro and Levaquin are the fluoroquinolones you’d recognize. Their sun risk sits in the middle of the pack, not the worst, not nothing.

The one with clean data is lomefloxacin, at roughly 4% to 10% of users. For Cipro and Levaquin, “moderate” is the honest word.

My take, and you can disagree. Finish the antibiotic, skip the beach day. The infection outranks the tan every time.

Just don’t stack a beach day on top of an antibiotic day if the calendar gives you any choice.

The Acne Drug That Cooks You In Five Minutes

Oral isotretinoin, the drug people still call Accutane, thins your skin’s outer shield. UV gets in faster, and not just on your face. Everywhere.

That sensitivity runs the whole four to six month course, and for months afterward while the barrier rebuilds.

One bad burn can leave dark patches for six to twelve months.

Accutane users report serious burns from five minutes outside. Five. Here, that’s not a warning. That’s a schedule.

If you’re mid-course and the trip is already booked, the timing question is worth real thought, because our winter midday UV runs 6 to 8 while summer runs 11 to 12.

That’s close to half the intensity for the same beach. It’s the actual argument buried in the honest case for when to come and when to stay home, and photosensitive people are the ones it matters most for.

Quick myth-bust while we’re here, because these two get mashed together constantly.

Topical tretinoin is not a true sun-sensitizer. The anti-aging cream irritates your skin so burns feel worse, and it breaks down in daylight, which is why you use it at night.

But it doesn’t drink UV the way the swallowed version does. Different drug. Different problem.

The Heart Pill That Can Turn Skin Gray

Amiodarone treats irregular heartbeats, so this one’s a smaller crowd. But it’s the strangest entry on the list.

More than half of people taking it become sun-sensitive.

A small share, under 10%, slowly turn a blue-gray, slate color on sun-exposed skin after a year or more. People call it “blue man” skin. The drug settles into the tissue and stays. 🔵

The kicker is the timeline. Amiodarone’s half-life sits near 57 days.

Sun sensitivity lingers 4 to 12 months after you stop.

You cannot undo this by skipping a dose the week of your flight. If someone you love takes it, shade isn’t optional for them.

The Motion Sickness Pill In Your Beach Bag

Packing something for the catamaran or the road to Hana?

Promethazine, sold as Phenergan, is a common pick for nausea. It’s an antihistamine in the phenothiazine family, and it triggers both phototoxic and photoallergic reactions.

Look at the setup though. You swallow it precisely when you’re about to sit on open water with no shade and full glare bouncing off the surface. 🚤

It’s almost perfectly engineered to hurt you.

Ask about a scopolamine patch instead. Same job, different chemistry.

The Herbal One With A Catch

St. John’s Wort contains hypericin, which is genuinely phototoxic. So it earns its spot.

But I’m going to be straight with you, because the internet loves to scream about this one.

At normal supplement doses, roughly 600 to 900 mg a day, the real-world risk is low. You’d need many times that to hit true phototoxicity.

The frightening lab numbers come from concentrated and IV forms used in cancer research, not the capsule from the vitamin aisle. 🌿

So don’t panic. Just don’t be the person who doubles up “for good measure” the week you’re standing under UV 12.

Number Nine Is Sitting In Your Carry On Right Now

Here’s the one I’ve been holding, and it’s the one that gets the most people, because nobody thinks of it as a drug at all.

NSAIDs. Aleve. Advil. The bottle rattling around your bag right now.

Naproxen is a documented sun-sensitizer. Ketoprofen is actually the worst of the family. Ibuprofen is milder but still on the list.

No prescription. No pharmacist. No sticker.

And naproxen has a genuinely nasty trick called pseudoporphyria. The skin turns so fragile it blisters and tears in sunlight, and it can scar.

One classic report followed 22 children on long-term naproxen who developed exactly that.

Now think about how a Hawaii day actually goes. Your back is wrecked from the plane. Your feet hurt from Diamond Head.

So you take two Aleve at breakfast and go sit on a boat for six hours. ⛰️

Nobody on earth would connect those two events. That’s the whole reason it’s number nine.

That’s the list. So what do you actually do about it?

What Actually Works And It Is Not More Sunscreen

Sunscreen is the answer everyone reaches for, and it’s the weakest one. Here’s the order that actually matters.

Timing beats everything. We treat 10am to 2pm as a no-go. The UH Cancer Center says avoid direct sun through 4pm.

Locals don’t beach at noon. We go early, come home, and go back out around 3 or 4 when the light turns gold and the sand stops burning your feet.

Nobody’s being virtuous. It’s just nicer.

Cloth Beats Cream

A UPF rash guard doesn’t sweat off, doesn’t rinse off, and doesn’t need reapplying.

ABC Stores sells a Hawaii Loa long-sleeve UPF 50 rash guard for $36.99, which is less than the good sunscreen you’ll go through in a week.

Wide-brim hat. Real sunglasses. That’s the kit.

It’s also, funnily enough, the opposite of what most people bring, which you’ll recognize the second you see the seven things locals laugh at tourists for packing.

Then sunscreen, and specifically zinc. Zinc oxide covers UVA1, the exact band doxycycline reacts to.

A high SPF number tells you about UVB. It can tell you almost nothing about the wavelength that’s actually your problem.

That’s the gap most people never close.

And make the phone call. Ask your doctor two things. Can the timing move, and how hard do I need to guard?

Bactrim clears in three days. Amiodarone takes the better part of a year. Only someone with your chart can tell you which conversation you’re having.

One more thing, because it’s the question everyone’s too embarrassed to ask.

If it does go bad, Straub Benioff’s Doctors on Call sits inside the Sheraton Waikiki at 2255 Kalākaua Ave, walk-in, 8am to 6pm daily.

And Longs Drugs at 2155 Kalākaua has the aloe. Buy it on day one, before you need it, and put it in the fridge.

Cold aloe on a fresh burn is one of those things that sounds like folklore until you feel it.

There’s one more rule people get wrong, and this one’s actually the law.

The Sunscreen Rule Tourists Get Wrong

Hawaii banned selling oxybenzone and octinoxate back in 2021. Fine. Here’s what almost nobody tells you.

On Maui, using non-mineral sunscreen breaks county law, not just selling it. Zinc oxide or titanium dioxide only.

Bringing your mainland bottle to Maui isn’t a shopping problem, it’s a rules problem.

On the Big Island, they deliberately left “use” out, so you can use what you brought, you just can’t buy it there.

Nobody’s taking anything off you at the airport. That myth needs to die.

If you’re buying here, Kokua Sun Care makes a 3 oz zinc SPF 50 for $32.99, and ABC Stores carries Maui Vera mineral SPF 30 at $14.99 for the same size.

The cheap one is not the bad one. It’s brand pricing, not island pricing, whatever you’ve heard about getting fleeced out here.

Now, my genuinely unpopular opinion. 🐠 The reef-safe law gets treated like the main event, and I think a chunk of it is theater.

Banning oxybenzone was reasonable. But warming water and land runoff are doing far more damage to our reefs than any tourist’s sunscreen ever did, and “reef-safe” on a label is barely regulated, so plenty of it is marketing.

Protect the reef. Just don’t let a label argument distract you from the fact that the sun is the thing actually trying to hurt you.

If that kind of straight talk is useful, it’s the same spirit as the rules locals wish every tourist read on the plane over.

My insider tip. Want Hanauma Bay with no crowd and no killer sun?

Reservations open exactly two days out at 7:00am at pros.hnl.info, and they evaporate.

But about a quarter of the capacity is held back for same-day walk-ins from 6:45am.

Show up at the gate at open, and you’re floating over the reef in low, soft light before the first tour bus leaves Waikiki.

It’s $25 to get in, $3 to park, and it’s closed Mondays and Tuesdays.

It’s also closed August 3 to 11 this year for sewer work, which is exactly the kind of thing that ruins a plan. Pau. That’s the whole trick.

Where To Stay When Your Skin Is The Problem

I’ll keep this short, because your skin is the story, not your room.

But shade, real AC, and covered pool areas turn a bad burn from a ruined trip into a slow morning.

Ko Olina is my pick if you want easy shade and calm water, and the Four Seasons Resort Oahu at Ko Olina sits right on the sheltered lagoons.

In Waikiki, Outrigger Reef Waikiki Beach has cabanas over the pool and puts you a short walk from that Longs.

On Maui, the Fairmont Kea Lani is all-suite with an adults-only pool and furnished patios, which matters when shade is medical rather than optional.

So that’s the nine, and the glass, and the 6:45am gate.

The part that still gets me is how ordinary it all is. There’s no villain here.

Just a bottle somebody’s taken every morning for six years, a rental car with the wrong windows, and a sun that doesn’t care how careful you thought you were being.

Book the early morning. Take the pill. Wear the shirt.

And that fingernail thing I mentioned Dave never got? It’s real, it’s called photo-onycholysis, and it shows up weeks after you’re home…