Guide//5 min
Coffee on a GLP-1
Nobody is going to tell you to give up coffee, and nobody should. But it interacts with three things this drug class has already made more fragile, and the interactions are all avoidable.
Medications
Ozempic
Semaglutide for type 2 diabetes — and everything that followed.
40 pieces
Guide//5 min
Constipation on a GLP-1
Nausea gets the attention because it arrives first and loudly. Constipation arrives in week three, never fully resolves for some people, and is the thing they eventually stop over.
Guide//6 min
Dehydration and your kidneys
Acute kidney injury on this drug class is almost never a direct drug effect. It is three days of vomiting in someone who did not think to replace the fluid, and it is entirely avoidable.
Guide//5 min
Teeth and dental work
Repeated vomiting erodes enamel permanently, reflux does it more quietly, and any dental procedure involving sedation now needs the same conversation as surgery. None of this is on the leaflet.
Guide//5 min
Diarrhoea on a GLP-1
A drug famous for slowing the gut down produces loose stools in a substantial minority, which sounds contradictory until you know what else is usually in the picture.
Guide//5 min
Donating blood on a GLP-1
No blood service in the United States defers you for taking one of these. What will defer you is the iron, the weight and the hydration — three things this drug class makes considerably more likely.
Explainer//6 min
A1c on a GLP-1
Roughly one and a half to two points for semaglutide, and more than two for tirzepatide. The more interesting question is why the number lags a month behind everything you are doing.
Explainer//6 min
GLP-1s and your period
Periods returning, periods changing character, periods arriving on a schedule for the first time in years. It is one of the most commonly reported effects in this drug class and one of the least documented.
Guide//5 min
GLP-1s before surgery
In 2023 the advice was to hold your weekly injection for a week. In 2024 a multi-society panel replaced that with something considerably more nuanced. Plenty of pre-op letters have not caught up.
Explainer//5 min
GLP-1s and cancer risk
The thyroid warning, the pancreatic scare and the colorectal signal are three different arguments with three different evidence bases, and the most consequential finding points the other way entirely.
Guide//6 min
GLP-1 dose charts, side by side
Four drugs, four different ladders, and a great deal of confusion about which rung anyone is standing on. Here is every approved escalation schedule in one place, with the reasoning behind the steps.
Explainer//5 min
GLP-1 drug interactions
These drugs are not metabolised by the liver enzymes that cause most interactions, so the usual list is almost empty. What replaces it is a single mechanical problem: everything you swallow now arrives late.
Explainer//5 min
GLP-1s and PCOS
These drugs address the insulin resistance sitting underneath polycystic ovary syndrome, which is why they work. Restoring ovulation in women who believed they could not conceive is the part nobody prepares for.
Deep Dive//5 min
The GLP-1 heart benefit
SELECT enrolled seventeen thousand people with heart disease and no diabetes, and found a twenty percent reduction in cardiovascular events. The label change that followed did more for access than any argument about obesity ever has.
Explainer//5 min
Every GLP-1 medication
There are more of these than the two everyone talks about, several are considerably older, and a few are still widely prescribed for reasons that have nothing to do with weight.
Explainer//6 min
Mood on a GLP-1
Regulators on two continents investigated whether these drugs cause suicidal thoughts and concluded they do not. That finding settles a narrow question and leaves a much larger one open.
Guide//5 min
GLP-1 pen problems
Almost every device problem people describe turns out to be one of six things, and the one that matters most is knowing when you have actually missed a dose.
Guide//6 min
How long side effects last
Almost every side effect in this class follows the same shape: bad after a dose increase, better within a fortnight, mostly gone by the time you have been at a dose for two months. Almost.
Explainer//6 min
The "natural Ozempic" question
Berberine, apple cider vinegar, fibre blends and anything sold as a GLP-1 activator. Some of them do something measurable. None of them does the thing they are being bought for.
Guide//6 min
Ozempic alternatives, compared
There are more approved weight-loss drugs than most people realise, and they are not close to each other in effect. Knowing the order matters, because plenty of plans will only cover the bottom of it.
Explainer//6 min
Ozempic face, explained
It is not a drug side effect. It is the face doing what the face has always done during rapid weight loss, in front of an audience that has never watched it happen this fast or this often.
Guide//6 min
Ozempic side effects, ranked
Most side-effect lists are alphabetical, which tells you nothing about what will happen to you. This one is ordered by frequency, with the trial numbers attached and the rare ones kept in proportion.
Explainer//6 min
Pancreatitis on a GLP-1
Almost everyone on this drug class gets abdominal pain at some point. A very small number of them have something that needs an emergency department that evening, and the difference is learnable.
Guide//6 min
Reflux on a GLP-1
A stomach that empties slowly is a stomach that stays full longer, and a full stomach lying flat has only one direction to go. Most of the fix is mechanical rather than pharmacological.
Guide//5 min
Heat, saunas and hot tubs
Heat lowers blood pressure and removes fluid from a body that is already short of both. Nothing about it is dangerous in isolation, which is precisely why people underestimate the stack.
Explainer//5 min
Semaglutide, explained
Ozempic, Wegovy and Rybelsus contain the same active ingredient. Almost every argument about which one you should be on is an argument about indications and insurance rather than about chemistry.
Guide//5 min
Switching between GLP-1s
The most common error when moving from semaglutide to tirzepatide is assuming your current dose buys you a head start. It does not, and the week you find that out is memorable.
Explainer//5 min
The thyroid cancer warning
Every box in this class carries a boxed warning about thyroid tumours in rodents. Fifteen years of human data have not confirmed it, and the warning is still there — for reasons worth understanding.
Guide//5 min
Travelling with your GLP-1 pen
The pens are more robust than people fear and less robust than a hot car boot. Most travel problems come down to three numbers and one decision about which bag it goes in.
Guide//7 min
What to eat on a GLP-1
Appetite suppression solves the quantity problem and creates a composition one. Every bite now has to do more work, and most people spend month one finding this out the hard way.
Guide//5 min
Where to inject your GLP-1
Abdomen, thigh or upper arm, and it genuinely does not matter which. What matters is the handful of things people do wrong in the ten seconds before the needle goes in.
Guide//2 min
Best supplements on semaglutide
Semaglutide's signature is gastrointestinal. Nausea, reflux and constipation shape what you can physically swallow, which makes tolerability the first ranking criterion rather than an afterthought.
News//3 min
The head-to-head trial, and what it settles
For three years the comparison between semaglutide and tirzepatide was made by holding two separate trials side by side, which is not a comparison. A direct trial changed that — and the result matters less to your decision than you would think.
Explainer//5 min
Ozempic or Wegovy: why you got the one you got
Ozempic and Wegovy contain the same drug. Which one lands in your hand is decided almost entirely by your insurance plan and your diagnosis code — not by your body.
Guide//5 min
How long Wegovy takes to work
Appetite usually changes in the first week. The scale takes considerably longer, and almost everything people believe about the timeline comes from watching someone else's month one.
News//3 min
The kidney indication
A trial stopped early for efficacy, a label expanded, and a benefit that has almost nothing to do with weight. If you have type 2 diabetes and chronic kidney disease, this is the most important thing in your file.
Explainer//5 min
The hair loss question
Hair shedding after starting a GLP-1 is real, common enough to be worth naming, and in most cases caused by the speed of the weight loss rather than the drug producing it.
Explainer//5 min
Semaglutide and the eye question
A 2024 study reported a higher rate of a rare optic nerve condition in semaglutide patients. Here is how to read a finding like that without either dismissing it or panicking.
Explainer//3 min
Semaglutide or tirzepatide
One is a GLP-1 agonist. The other adds GIP. The trial data favor one of them on weight — which is not the same as saying it is the right one for you.
Explainer//5 min
GLP-1s and alcohol
A striking number of people on these drugs report simply losing interest in alcohol. It was nobody's design goal, the mechanism is unresolved, and it may turn out to be one of the most consequential things this class does.
Also in Medications
On The Jab
The
GLP‑1
Handbook
Dr. Nick Robertson
MD
The book · 14 chapters
The GLP-1 Handbook
Everything I tell my own patients before their first injection. 214 pages of what actually matters in the first year — dosing, side effects, food, muscle, cost, and the part nobody prepares you for: maintenance.
$4Less than your morning coffee.
Priced at four dollars because it should be affordable to everyone taking these drugs — not because it's worth four dollars. No upsell, no course, no supplement line.