Why do I feel nauseous or keep vomiting?

Both semaglutide and tirzepatide slow down how quickly your stomach empties. This is actually part of how they work — it helps you feel full longer — but the trade-off is that food and acid sit in your stomach longer than usual, which causes nausea and, in some people, vomiting. This effect is strongest when you first start the medication or go up to a higher dose, and it typically settles down over a few weeks.

Can this medication cause heartburn or acid reflux (GERD)?

Yes — GERD (heartburn / acid reflux) is reported in roughly 2–5% of people on semaglutide, dulaglutide, and liraglutide, and had a significant signal across all GLP-1 medications in pharmacovigilance data. About 1 in 5 people on GLP-1 therapy develop some degree of delayed stomach emptying, and semaglutide specifically carries a notably higher gastroparesis risk compared to other weight-loss approaches. If you already have reflux or a hiatal hernia, GLP-1 therapy can make it worse — let us know before starting.

Can reflux become serious — and when do we stop the medication?

In most people it's mild and manageable — but if vomiting is ongoing, repeated acid exposure can lead to reflux oesophagitis (inflammation of the oesophagus lining). Rare case reports have documented severe presentations requiring endoscopy. This is why we don't tell patients to just "push through." Our step approach: first, slow or pause dose escalation; if symptoms remain significant, consider a temporary hold or dose reduction. A PPI (like omeprazole) is our first-line prescription, with a mucoprotective agent added in stubborn cases. We also ask you to avoid stomach-irritating drugs concurrently — bisphosphonates (bone medications) and dabigatran (a blood thinner) in particular.

If GERD/oesophagitis is severe, or vomiting is refractory: we discontinue semaglutide. The good news is that symptoms and mucosal injury typically resolve after stopping. If you still want to stay on a GLP-1 medication, we can cautiously trial a switch to a different agent — individual tolerance varies, even though all GLP-1 therapies share a similar GI profile.

Why does food taste strange or metallic?

Dysgeusia (bad taste in the mouth) can feel metallic, salty, rancid, or even burning, and can start within a couple of weeks. Two things drive it: GLP-1 medications appear to alter taste receptor signalling directly, and slower stomach emptying causes bile and acid to reflux up, leaving a foul taste. It's more common with oral semaglutide (Rybelsus) than the injectable — if you're on Rybelsus, try taking it with hot water (46–52°C), which reduces bitterness without affecting how the drug works.

What we look for first: Before assuming it's just the medication, we check for contributing factors — uncontrolled acid reflux (treating GERD often improves the taste), oral thrush (candidiasis), dry mouth (xerostomia), and other medications you may be on (such as metformin, which can independently affect taste). Acidic and spicy foods often worsen dysgeusia, so dietary adjustments help. Good oral hygiene, saliva-stimulating measures (sugar-free gum, mints, staying hydrated) are the everyday backbone of management. If taste changes are troublesome and persistent despite addressing GERD and other contributing factors, we discuss dose reduction or switching to a different GLP-1 — weighing that against your glycemic and weight-loss benefits, keeping in mind that dysgeusia on its own is generally rare and often resolves.

Why am I so tired since starting the medication?

Fatigue is one of the most common — and most under-talked-about — side effects of GLP-1 therapy. The good news: in most people it follows a predictable pattern, and it lifts on its own.

Why does it happen? Eating less means fewer calories in, your blood sugar runs lower and steadier (no big spikes or crashes), and the body is doing real metabolic work as it adapts. Mild dehydration and lower-than-usual carbohydrate intake can quietly add to it. None of this is dangerous on its own — it just feels like a slow battery.

What helps day-to-day: drink water before you feel thirsty, prioritise protein at every meal (your appetite is suppressed, but your needs aren't), don't skip meals just because you're not hungry, keep gentle movement in your week (a daily walk often helps more than rest), and protect your sleep — early nights make a real difference in these first weeks.

Why is my sleep different — light, vivid dreams, waking earlier?

A lot of patients notice subtle changes to their sleep in the first 6 to 8 weeks of GLP-1 therapy. The classic trio is lighter sleep, vivid (sometimes strange) dreams, and waking earlier than usual. It's unsettling if no one's mentioned it — but it's a recognised pattern, not a sign anything is wrong.

Why does it happen? The full mechanism isn't completely worked out, but GLP-1 receptors are present in brain areas that help regulate sleep, appetite, and the body's day-night rhythm. When you start a GLP-1, that central activity can nudge sleep architecture — particularly REM (the dreaming stage) — for a few weeks until your brain settles into the new pattern. Lower evening calorie intake and steadier overnight blood sugar also play a small role.

When to flag it: nightmares that are distressing or recurrent, daytime sleepiness severe enough to affect driving or work, loud snoring with witnessed pauses in breathing (possible sleep apnea — common in people carrying extra weight, and treatable), or low mood and morning despair. Any of these warrants a review — they aren't typical "GLP-1 sleep changes" and shouldn't be brushed off.

Can semaglutide cause low blood sugar (hypoglycemia)?

Very rarely on its own. Semaglutide is glucose-dependent, which means it only nudges your pancreas to release insulin when your blood sugar is already high. When your blood sugar is normal or low, semaglutide essentially steps back — so it can't drive sugar levels down on its own the way insulin or sulfonylureas can. In the SUSTAIN trial programme, hypoglycemia rates in people without diabetes were close to placebo.

How to tell the difference at home: if you have a glucometer, check your sugar when you feel "off." A reading under 4.0 mmol/L is a true hypo and needs 15 g of fast-acting sugar (e.g. 4 glucose tabs, ½ cup juice, 1 tbsp honey), retest in 15 min. If your sugar is normal but you still feel shaky, it's almost always not enough food or fluid — that's a fix you make at the table, not with the medication.

Will these side effects go away on their own?

For most people — yes. GI side effects peak when you first start or go up to a new dose, then typically settle over a few weeks. Taste changes usually improve as your body adapts, though for some they persist throughout treatment. Slower dose escalation is the single most effective prevention. Never rush up to the next dose while symptoms are still active. If things aren't improving after 4–6 weeks at a stable dose, let us know — we have options beyond just waiting.

What can I do at home for heartburn and nausea?

Lifestyle habits that make the biggest difference: eat smaller, low-fat meals; avoid eating in the 2–3 hours before lying down; don't eat late at night; elevate the head of your bed slightly; stay upright after meals. For heartburn, an H2 blocker (like famotidine/Pepcid) gives quick relief. If that's not enough, talk to us about a PPI (like omeprazole) — it's our first-line prescription. Never increase your medication dose while GI symptoms are still active.

Anything I should avoid that makes this worse?

Yes — a few things can add insult to injury when the stomach is already irritated: carbonated drinks, alcohol, caffeine, fatty or spicy meals, and late-night eating all make reflux worse. Importantly, certain medications also irritate the stomach lining and should be avoided or discussed with us if you're on them — especially bisphosphonates (e.g., alendronate for osteoporosis) and dabigatran (a blood thinner). These are not necessarily stopped, but the timing and combination need to be reviewed.