Weight Loss Pills in Hong Kong: Orlistat (Xenical) and Rybelsus

The shelf of 減肥藥 in Hong Kong is crowded, and for most of what sits on it the evidence is thin or missing. Two of the medicines people ask about most have real trial data behind them: orlistat and semaglutide. We read the NHS pages, the US labels, the NICE appraisal, two trials and the Department of Health's warnings.

In short

• Orlistat works in the gut, reducing how much of the fat in your food is absorbed, so about a third of it leaves the body in the poo.
• The dose is 120 mg three times a day with main meals, and after a year it gives about 3 percentage points more weight loss than placebo, with a larger share of people losing at least 5% of their starting weight.
• Rybelsus is a once-daily semaglutide tablet licensed for type 2 diabetes; using it for weight loss is off-label.
• Wegovy, Saxenda and tirzepatide are injections, PockDose lists none of them, and they come up here as context only.
• The Department of Health has warned repeatedly about slimming products containing hidden sibutramine, banned in Hong Kong since November 2010.

How does orlistat work, and what does it do for weight?

A fatty meal is normally broken down and absorbed in the small intestine. Orlistat works there rather than in the brain: it reduces the amount of fat absorbed, and about a third of the fat from your food is passed out in the poo (NHS, orlistat).

That effect depends on what you eat. The label dose is 120 mg three times a day, with each main meal that contains fat, taken during the meal or up to an hour afterwards (DailyMed, Xenical label). The diet it is designed around gets about 30% of its calories from fat, and doses above 120 mg three times a day give no added benefit. The trials below all used the 120 mg dose.

What that adds up to is modest but real. Across five one-year trials covering 2,680 people, mean weight loss on orlistat was about 3% greater than on placebo, and the share of people losing at least 5% of their weight was higher in every trial, including 54.8% against 27.4% in one of them. The longest study, XENDOS, followed 3,305 adults with a BMI of 30 or more for four years on orlistat 120 mg three times a day plus lifestyle changes, against placebo (XENDOS, Diabetes Care 2004). Mean weight loss was 5.8 kg on orlistat and 3.0 kg on placebo. New type 2 diabetes appeared in 6.2% of the orlistat group against 9.0% on placebo, a 37.3% reduction in risk explained by the 21% of people who started with impaired glucose tolerance.

How do you take orlistat, and what side effects should you expect?

Orlistat is tied to your meals rather than to a clock. Take a capsule with a main meal that contains fat, during the meal or up to an hour after it, and skip that capsule if you miss the meal or the meal has no fat in it. If you remember a missed dose within an hour of eating, you can still take it. Later than that, leave it.

Fat-soluble vitamins need some planning. Take a multivitamin once daily at bedtime, or at least two hours before or after the capsule (DailyMed, Xenical label). Levothyroxine needs at least four hours between the two, and ciclosporin is taken three hours after orlistat. The label also reports a loss of effect with warfarin, amiodarone, antiepileptics and antiretroviral (HIV) medicines, so tell whoever prescribes those that you are taking orlistat.

The side effects people notice are the ones that show the medicine working. Oily spotting, wind with discharge, fatty or oily stool, needing to poo urgently or more often, and sometimes accidental leakage are the common ones, each reported by at least 5% of people in trials and at least twice as often as on placebo. They are less likely on a balanced diet without very high-fat meals, so spread the fat across the three meals rather than eating it all at once.

A few serious effects are rare and worth knowing by name. Severe tummy or back pain that does not go away can be acute pancreatitis, and a swollen throat or tongue, an itchy rash or difficulty breathing is an emergency. Any sign of liver trouble means stopping the capsules and getting medical help, because severe liver injury has been reported. The US label also lists oxalate kidney stones and gallbladder disease.

With a combined contraceptive pill, severe diarrhoea, or diarrhoea lasting more than 24 hours, may mean the pill does not protect you; use condoms as well until it settles (NHS, orlistat). The NHS also advises against continuing beyond three months if you have not lost 5% of your body weight. Orlistat is not suitable with cholestasis, chronic kidney disease, or a condition that stops vitamins and minerals being absorbed. Weight loss offers no benefit during pregnancy, so orlistat is stopped when pregnancy is found; the NHS says it is not used in pregnancy and not usually while breastfeeding.

What is Rybelsus, and is it a weight loss pill?

People ask about Rybelsus because the injections are everywhere and a tablet sounds easier. It is semaglutide in tablet form, a GLP-1 agonist licensed as an adjunct to diet and exercise for blood sugar control in adults with type 2 diabetes (Rybelsus label, FDA). It is not for type 1 diabetes.

Semaglutide lowers blood sugar, helps the body make insulin when it needs to, and slows digestion. For weight, the useful part is appetite: it reduces how hungry you feel and helps you feel fuller for longer (NHS, semaglutide). Using Rybelsus for weight loss is off-label, since it is licensed for type 2 diabetes. We do not guarantee the effect, and official references do not recommend that use.

The numbers people quote tend to come from two trials, and neither belongs to the tablets in the 3, 7 and 14 mg strengths. STEP 1 gave 1,961 adults without diabetes a once-weekly 2.4 mg semaglutide injection or placebo for 68 weeks. Mean weight change was -14.9% against -2.4%, and 86.4% against 31.5% lost at least 5% of their weight (STEP 1, NEJM 2021). That is the injection.

OASIS 1 did test a tablet, at a dose far above anything Rybelsus contains: oral semaglutide escalated to 50 mg daily against placebo for 68 weeks in 667 adults with overweight or obesity, giving a mean weight change of -15.1% against -2.4%, with gastrointestinal side effects in 80% against 46% (OASIS 1, Lancet 2023). 50 mg is more than three times the highest Rybelsus tablet. The trial gives no figures for the 3, 7 or 14 mg tablets, and nothing in these pages shows weight results for the 14 mg tablet.

How do you take Rybelsus, and who should not?

Rybelsus has a morning routine you cannot move around. Take it as soon as you wake, with no more than 4 ounces, about 120 ml, of plain water, and swallow the tablet whole (Rybelsus label). Then nothing goes in your mouth for at least 30 minutes: no food, no coffee, no other tablets. The NHS describes it as an empty stomach with no food for at least eight hours beforehand (NHS, semaglutide). Missed a tablet? Skip it and carry on the next morning.

The dose steps up. Start on 3 mg once daily for 30 days, a starting dose only and not one that controls blood sugar, then move to 7 mg, and to 14 mg after at least another 30 days on 7 mg if more is needed.

Two groups should not take it at all: anyone with a personal or family history of medullary thyroid carcinoma, and anyone with MEN 2, multiple endocrine neoplasia syndrome type 2. The label carries a boxed warning that semaglutide causes thyroid C-cell tumours in rodents, and it is unknown whether it does so in humans. A neck lump, trouble swallowing, persistent hoarseness or shortness of breath should be checked.

Pancreatitis appeared in trials, six cases on Rybelsus against one on comparators. Severe stomach pain that goes through to the back means stop and get urgent care, and the medicine is not restarted if pancreatitis is confirmed. The label also flags gallbladder disease, acute kidney injury and worsening diabetic retinopathy, and the NHS adds sudden loss of vision. If you take insulin or a sulfonylurea, low blood sugar is a real risk.

The common side effects are nausea, stomach pain, diarrhoea, decreased appetite, vomiting and constipation. Alcohol makes nausea and vomiting worse. Rybelsus is not used in pregnancy: stop at least two months before a planned pregnancy, and it is not recommended while breastfeeding. It interacts with warfarin, levothyroxine, insulin and other diabetes medicines, and stopping it suddenly is not advisable in type 2 diabetes.

What about the injections, and the slimming products the Department of Health keeps warning about?

Wegovy is the weekly semaglutide injection for obesity, while Ozempic (weekly injection) and Rybelsus (daily tablet) are the type 2 diabetes forms (NHS, semaglutide). Saxenda and tirzepatide are the other names that come up in 減肥針 searches. PockDose lists none of the injections.

NICE's guidance on semaglutide for weight is narrow. TA875 recommends it alongside a reduced-calorie diet and more activity only within a specialist weight management service, for a maximum of two years, in adults with at least one weight-related condition and a BMI of at least 35, or 30 to 34.9 with referral criteria met (NICE TA875). For people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds, lower BMI thresholds apply, usually 2.5 kg/m² lower. Stopping is considered if less than 5% of starting weight has gone after six months. TA875 covers the weekly injection, not Rybelsus.

The Department of Health's warnings are about a different sort of product. In July 2016 it reported a 43-year-old woman admitted to Tuen Mun Hospital with psychotic symptoms after drinking a slimming product called Lose Weight Coffee, bought from a van in Sham Shui Po; the Government Laboratory confirmed sibutramine in it (DH, 2016). Sibutramine was once used as an appetite suppressant and has been banned in Hong Kong since November 2010 because of increased cardiovascular risk.

In June 2021 the department warned about 2WEEKS, sold through social media and found to contain undeclared sibutramine (DH, 2021). Earlier, in 2009, the Centre for Health Protection found undeclared sibutramine and a sibutramine analogue in Slim Pure and Ku Xiu Ba Xiang Jian Fei Wan, after members of the public who had bought online asked about them (CHP, 2009). Sibutramine raises blood pressure and heart rate, and people with heart problems should not take it; an analogue is expected to behave the same way.

The Department of Health's advice is blunt: do not buy products of unknown or doubtful composition, and do not consume products from unknown sources. A named medicine with a known ingredient and a known dose is a different thing from a coffee sachet with a vague label.

Which weight loss medicines does PockDose list?

Our weight management listings are generics. 賽尼可 and 奧利司他 are the Chinese names for Xenical and orlistat.

Which one fits depends on what you want the medicine to do. Orlistat works in the gut on the fat in your meals, while Rybelsus works on appetite and blood sugar. Read the product page before ordering. Clenbuterol is an asthma medicine, and we do not guarantee any weight effect: official references do not recommend that use. No prescription is needed to order from PockDose. The wider weight loss category and type 2 diabetes ranges sit alongside these listings, and the orlistat and semaglutide pages cover the ingredients.