All opioids (e.g. heroin, fentanyl, oxies, methadone) have a range of effects. Some are desirable and some aren’t.     

If you’re starting on methadone or bupe, you would have been using street and/or pharmaceutical opioids for a while, so you’ll probably be used to many of the side effects. You might not notice or even experience them anymore. In fact, some disappear after the first month or so.    

Here are some common side effects from being on methadone, buprenorphine, and other opioids, to help you better understand what to expect and how to manage them. If these are ongoing issues for you, you should talk to your doctor/prescriber about them – you might need to adjust your dose or change medication.  

Dependency and withdrawals 

You might think it’s all a bit obvious to say that all opioids, whether derived naturally or manufactured in a lab, are habit-forming.  But one of the biggest complaints we get about methadone and bupe is that people didn’t realise how hard it was going to be to come off them. They are harder to withdraw from than heroin and that keeps a lot of people on the program longer than they want.  

The thing is, the reason they work so well as a treatment is the very thing that makes them harder to get off. We only need to dose every 24 hours (and can double dose with bupe to make it last 48 hours) and it builds up in our system so we get that even, stabilising effect. 

The ‘half-life’ of a drug is a way to measure how long drugs last in our bodies. Half-life is the time it takes for half the dose to break down or leave the body. Heroin has a half-life of between 3 and 10 minutes, after which your body turns it into morphine. Morphine has a half-life of 20 minutes to 6 hours. Because of its shorter half-life, you can detox from a heroin habit in around 4 to 7 days.  

On the other hand, methadone’s half-life is between 8 and 60 hours, and buprenorphine’s half-life is between 24 and 42 hours. Their long half-lives make them suitable for opioid treatment because it provides a stable and even drug-experience and you only need to dose once a day or less. The disadvantage is that once you stop taking them, the detox takes much longer. 

The symptoms of withdrawal from methadone and buprenorphine are the same as other opiates. You will experience flu-like symptoms, sleeplessness, diarrhoea, cramps, anxiety, irritability, depression and cravings. 

What can I do about it? 

You can’t avoid dependency if you are on a program. However, when it comes to getting off it, you can make withdrawal easier. It’s all about planning, coming off gradually and treating your withdrawal symptoms. 

When it comes time to withdraw from methadone and buprenorphine, the best technique is to reduce to as small a dose as you can. Some people find that swapping from methadone to bupe (or vice versa) when they’ve reduced to a small dose can also make withdrawal easier. 

Ask your doctor and other support health workers as well as your friends and peers to help you deal with the pain and anxiety that comes with detox. The most successful approaches combine a mix of tactics, like exercising and eating healthily, medication, and counselling. Meditating, massages, yoga, and alternative medicine (like acupuncture and herbal remedies) can also be helpful for some people. 

Hormonal issues 

High doses of opioids can affect sex hormones – both street opioids (e.g. heroin) and prescription opioids (e.g. methadone and bupe) will do this.  

Taking opioids can cause sexual dysfunction (low libido) for male and female users. This might just mean being less interested in sex, or it could mean you can’t get or stay turned on.  

While there are links between reduced testosterone and opioid use, there are many other reasons why someone might experience sexual problems, including depression, stress, sleep issues, smoking and menopause.  

In women, hormone issues can lead to irregular periods and while we need more research, women on the OTP say they start menopause earlier than the usual 48 – 55 of the rest of the population. It’s easy to think you need to go up on your dose, because the symptoms of menopause are similar to opioid withdrawal. Menopause can also reduce your sex drive. 

What can I do about it? 

A good place to start with the libido issue is to think about what else could be making you feel this way.  Are you too busy or too stressed? Is it about the demands of parenthood? Do you find it challenging to hook up without a load of drugs on board? Keep in mind that part of the problem can also be related to too much alcohol, tobacco and some other drugs. 

Older women having lighter and irregular periods should see their GP for tests to find out if they are starting menopause. There are hormone replacement treatments and/or meds to help with menopausal symptoms. Younger women with low sex drive can also access hormone replacement in some circumstances. 

Men with low sex drive should see their doctor to have their testosterone levels checked. If they’re low, they may get replacement therapy.   

Ask for a referral to a specialist if your GP doesn’t have any answers for you.  

Poor sleep  

People on opioids often don’t sleep well. You might get night sweats, have problems with breathing and snoring (sleep apnea), or wake up mid-sleep (often to urinate). Sleep problems can lead to poor concentration, a lack of energy throughout the day, headaches, depressed mood, and sexual dysfunction. 

Poor sleep might happen for a variety of reasons, some related to opioids. Sleep apnea is when your airways are partially or completely blocked while sleeping – this can be made worse by opioids but might also be a sign of larger issues (like heart problems).  

What can I do about it? 

Talk to your GP to find out if your sleep issues are something to be concerned about (you might have to do a sleep study). Anxiety, depression or stress may be the cause. Your GP can help you make a Mental Health Plan – from there, you might try counselling or a course of anti-depressants. 

Alternatively, your prescriber can help you tweak your dose or suggest a better time to dose. Your dose may be too low, causing withdrawals at night, or you may be having your dose too late at night which could be overly stimulating.  

There are also plenty of things you can do to help yourself if you are having trouble sleeping. There are some great books and websites with tips and techniques about how to get yourself into a healthy sleep pattern. These include going to bed and waking up at the same times each night, not reading in bed, not eating or drinking coffee after a certain time, practising meditation, getting massages and exercising each day so you are tired out for bedtime. 


Feeling drowsy is a common side effect of opioid use. High doses of any opioid will cause drowsiness, ranging from mild tiredness to difficulty in staying awake. Mixing depressant drugs with other depressant drugs, such as other opioids, benzos, Lyrica and alcohol, can make drowsiness even more extreme.  

What can I do about it? 

If you’re feeling constantly drowsy, you should talk to your GP to rule out any medical conditions (e.g. sleep apnea, hepatitis, heart problems). It could be that your dose is too high, so talk to your prescriber about adjusting it.   

In the short-term, if you are noddy try getting some fresh air and keeping your body moving. Don’t drive or operate heavy machinery. Not only might you fall asleep at the wheel, your concentration and coordination are affected. We would miss you. 

Bone and muscle pain 

A lot of people think that being on an opioid treatment program can lead to your bones ‘rotting’, or that the ‘methadone gets in your bones’. This is a myth.  

Some men on the OTP have low bone mass density, but studies suggest that while it’s picked up when they are on the program, it’s caused from using street opioids (e.g. heroin). All long-term opioid-use can decrease sex-hormone levels, especially in men which can lead to low density bones and osteoporosis.  

Tobacco smoking, poor diet, living with HIV and heavy alcohol use also contribute to issues with your bone and muscle health.  

What can I do about it? 

If you are feeling aches and pains in your bones and muscles, it’s more likely a sign of minor withdrawals, so if this problem persists you may need to go up on your dose.  

Getting the right nutrients in your diet is important so eat dairy and talk to your doctor about a calcium and/or magnesium supplement.  

Heart Issues 

Opioids can affect your heart in a range of ways, primarily because they are ‘depressant’ drugs which slow down your central nervous system. Some heart-related side effects of methadone, bupe and other opioids are low blood pressure, slow or irregular heart rate, and a faint heartbeat.  

There are some ways that methadone specifically can interact with other substances which can affect the way your heart beats. If you have a family history of heart problems, it’s worth talking to your prescriber about it. If you are on a high dose, your prescriber may want you to do some tests to see how your heart is functioning.  


A lot of people think that opioids can make them gain or lose weight, although there is little evidence to suggest this belief is true. Using opioids can cause your body to retain more fluid, which might contribute to weight gain – this is more commonly an issue experienced by women than men. 

Some people put on weight while on the program, but this is more likely because on the program you’ll be running around less and eating more.  Other medications, such as antidepressants, can also affect your weight.   

What can I do about it? 

You’ll probably have more money for food while you’re on the program, so it’s a good idea to look at a healthy eating plan. Think about limiting junk foods you might buy to “reward” yourself for not using. If you don’t have any  energy, avoid chocolate and look at your sleep patterns and your depression and/or anxiety levels. Talk to your doctor if you’re concerned about weight change and get a long-term food and exercise plan to support you when gaining or losing weight. 

Dental Issues 

Another myth of being on methadone or buprenorphine is that it ‘rots your teeth’ – this just isn’t true! It may be that when you get on OTP you start noticing this stuff more, but chances are it’s partly about ageing and partly about not getting to the dentist when you should because of the high cost. Teeth are also damaged by smoking, vomiting, drinking alcohol, bad diet, not brushing and flossing enough, not drinking enough water and injuries to the mouth. 

The biggest culprit is probably ‘Dry Mouth Syndrome’ aka Xerostomia, which is a condition when your mouth doesn’t produce enough saliva. Dry Mouth is common – it is a side effect of over 300 medications, including all opioids – street drugs as well as methadone and buprenorphine, and anything starting with ‘anti’ – like antidepressants, anticoagulants and antibiotics.  

Using stimulants also has its own problems, including the fallout from grinding your teeth. 

What can I do about it? 

The best ways to deal with dental issues while on methadone, buprenorphine, or any other opioids, is to keep good oral hygiene in general. Try to brush and floss your teeth twice a day and, if possible, aim to get to the dentist to get your teeth professionally cleaned. Limiting the amount of processed and sugary foods you eat, and avoiding acidic or carbonated drinks, can also help keep your teeth in good condition. Dentists tell us the #1 best thing you can do for your teeth is to not smoke. 

It’s also important to avoid your mouth staying dry for long periods of time. There are special products on the market to treat Dry Mouth Syndrome. You should also chew sugar-free gum after eating to increase your saliva, drink tap water regularly and sip water whenever you notice your mouth is dry. 


Some people experience nausea (feeling sick to the stomach) when they’re on the program. There are several reasons you could feel this way. Nausea in the mornings might be a sign that you’re hanging out – you might want to talk to your doctor changing your dose. People can also feel queasy if they go up on their dose too quickly. 

What can I do about it? 

Methadone or bupe just don’t sit well with some people, so if you’re experiencing ongoing nausea past the first month of treatment you might want to talk to your prescriber about trying the other medication. Lying down, as horizontal and still as possible, can sometimes help reduce nausea caused by opioids.  

If you get regular nausea (like with migraines or pregnancy) talk to your prescriber about splitting your dose, having part in the morning and part in the afternoon or maybe going on physeptone, the tablet form of methadone. They may not agree but you can only try. 


Headaches are a common side effect in the early days of opioid treatment, while your body is getting used to your medication. You might also get headaches if you go up or down on your dose.  

What can I do about it? 

Unfortunately, there isn’t a lot you can do about them – your best bet is to drink lots of water and try to get enough sleep. Over-the-counter, non-opioid painkillers like Ibuprofen (Neurofen), Paracetamol or Aspirin can also help.  If your headaches persist for more than a month after being on a stable dose, talk to your doctor about them as they may be symptoms of a larger issue. 


Some people experience constipation from using opioids. The opioids bind to the stomach (gut), causing blockages. This is especially common when you take large, regular doses of opioids and can be a frustrating problem to deal with. 

What can I do about it? 

Prevention is better than cure, so the simplest thing is to avoid constipation by eating more fibre (wholegrain or multigrain bread, nuts and cereals), as well as lots of fruit and vegetables. Drinking lots of water is essential. Hot drinks, tea and coffee may also help get things moving. Prunes or warm prune juice is famous (or infamous) for ending constipation.  

Exercising regularly will also help: a 10-minute run, some light stretches and yoga are particularly good at helping with constipation. Going to the toilet at the same time each day can also help.  

Some people experiencing a blockage will simply delay a shot or dose til they experience withdrawal symptoms, including loose stools. A bit radical. but if the alternative is the pain and inconvenience that comes with a blocked back passage, it may be worth it. 

We prefer you try this gold medal standard for helping to push out a blockage. Set the scene properly – give yourself time and privacy, flood your intestines by drinking heaps of water and do some butt squeezes. Then get on the toilet, raising your feet up off the floor by putting them on a low box. Even going tippy-toes can help. You want to get all your muscles in the best place to push, and for that you need a position that is closer to squatting than sitting up straight on a seat. You can actually buy products that are the right height (google “toilet foot stool” or “squatty potty”) but the trick is to be squatting, so raise your legs around 20 to 30 cm.  

You can also try pharmacy medicines like laxatives and stool softeners. If you do end up with an extremely serious case of an ‘impacted’ stool (when your intestines are full of hard, dry matter that you just can’t push out), try a suppository from the pharmacy (they go in the anus and draw water into the intestines). If that doesn’t work, you may need an enema. You can go to your GP or a private Colon Health Clinic or learn to do this at home. Then take every step to stop it happening again! 


Another very common side effect from methadone and bupe is sweating more than usual – about 45% of patients experience this. Sweating might be because of the effects that opioids have on the part of our brain that controls body temperature, but we don’t know for sure. Methadone sweats seem to be much worse than sweating from bupe or other opioids.  

What can I do about it? 

 If you’re sweating a lot, it’s best to ask your doctor what they think, as it could be a sign of another issue like kidney problems or an infection. Sweating can also be a sign of withdrawals, so if you’re experiencing other withdrawal symptoms you might need to go up on your dose. Note that excessive sweating is also a symptom for some people who have hepatitis C, so if you have hep C and get it treated, there is a good chance your sweating might stop or ease up.  

If it’s not from withdrawals or other health conditions, you could think about reducing your dose, although that won’t help everyone. You may need to treat the side effects.  

When you sweat, your body loses fluids, so to avoid getting dehydrated you should aim to drink at least 2 litres of water each day.  

You might want to try using a high end “clinical strength” anti-perspirant / deodorant marketed to people who sweat a lot. (Note: anti-perspirants stop sweat; deodorants stop smell). There is even a gel that stops your face sweating (great for wearing under make-up). Talk to your doctor or chemist about the different sprays, gels and even tablets designed to help. Put products on when you wake up and before you go to bed and as many times during the day as you need it. You can also apply talcum powder to your sheets and your body where you sweat the most.  

There are other things you can do to help. Think about your clothes (and your sheets etc). Synthetic fabrics will make you sweat more and loose clothing will help you control your sweating better. Diet also makes a difference – do some research or get a referral to a dietician because some foods make you sweat more. Getting sweat out during exercise often helps control it at other times and here’s a simple one: if you don’t want to arrive somewhere in a flustered, wet mess, allow yourself plenty of time to get there.