Paramol vs Codeine: Is Dihydrocodeine Really Stronger?

"Is Paramol stronger than co-codamol?" "What about Solpadeine?" These are questions we see the most in regards to pain relief. As Paramol combines paracetamol with dihydrocodeine and co-codamol, Solpadeine Plus and Solpadeine Max contain codeine alongside paracetamol. So people mainly want to know what if any the difference is between the two opioids and does replacing codeine with dihydrocodeine actually make a worthwhile difference?

There is some evidence that dihydrocodeine is stronger than normal codeine. Paramol’s summary of product information does state that 30mg of dihydrocodeine has the pain-relieving potency of 60–120mg of codeine, but this might be slightly exaggerating its potency a little bit. ^[1]

A 2010 review described dihydrocodeine as probably twice as potent as codeine by injection, but only slightly stronger when taken by mouth. So while it is twice as strong by injection as Paramol’s SPC states the same 2x potency was not seen when taken orally.

The UK Faculty of Pain Medicine guidance puts oral codeine and dihydrocodeine at the same approximate potency. But not that these figures are there to help clinicians estimate doses when switching opioids, and the guidance acknowledges that the evidence is incomplete and individual responses vary.

Do not dismiss the possibility that oral dihydrocodeine is a little more potent, it's just hard to say how much more potent it is and if you will find it provides any more relief than normal codeine does.

Codeine’s pain-relieving effect depends largely on your body converting some of it into morphine, using an enzyme called CYP2D6. Some people do this poorly and then get little benefit from the codeine itself. Others convert it unusually quickly, increasing the risk of serious side effects rather than simply giving them better pain relief. ^[2]

Your other medicines can affect this too. Fluoxetine and paroxetine, for example, can inhibit this enzyme and reduce codeine’s effectiveness. So an apparently weak response is not necessarily a sign that you need a higher dose.

Dihydrocodeine may behave differently. In a 1998 study involving 11 healthy volunteers, researchers blocked CYP2D6 and substantially reduced the formation of dihydromorphine, one of dihydrocodeine’s breakdown products. Despite this, they found no significant reduction in its effects on pain tolerance. ^[3] This suggests dihydrocodeine’s pain-relieving action may be less dependent on that conversion. This is a very small study, so a proper conclusion cannot be drawn but it could be something to consider when choosing a pain relief medicine. 

Paramol is not totally free from metabolism-related precautions. Its prescribing information warns that CYP2D6 differences can affect its response and safety, and it must not be used by people known to be ultrarapid metabolisers.

I wouldn’t treat co-codamol, Solpadeine Max and Paramol as a ladder you work your way up, or assume there is one "strongest" option that will work the best for everyone. When selecting a painkiller what you want to do is to find something suitable that relieves your pain, at the lowest effective dose for the shortest time possible.

If someone comes in or asks online what they should take and they haven't tried anything yet, plain paracetamol would often be my starting point, depending on the type of pain. These opioid combinations are intended for pain that simpler painkillers haven’t relieved or more serious causes, not as an automatic first choice for every type of pain. If paracetamol does the job, there’s no reason to add an opioid into the mix.

Past experience helps, if someone tells me Paramol worked well for them before I’d be more likely to suggest it again, but just doesn’t mean I’d tell the next person that asks that Paramol will work better for them too.

I’d also ask what exactly what "better" means. Was the pain noticeably reduced? Could you eat or move more comfortably?

Take what you need to relieve the pain, not the strongest thing you can buy.