Tables and diagrams

We’ve collected key tables and diagrams in the guide here for ease of reference.

Figure 1. Viral load blips

Fig 1 viral blips

Figure 2. Viral load rebound

changing 2015 Fig2 confirmed viral rebound

Figure 3. From rebound to symptoms

Fig 3 time from viral to clinical failure

Figure 4: How one mutation can stop some drugs working

Graph showing 1 mutation causing extensive resistance.

Figure 5: Resistance increases slowly with some drugs

Graph showing number of mutations increasing from 1 (low resistance) to 6(extensive resistance)

Figure 6: Drug levels with good adherence

Graph showing drug levels staying within a band where there is less risk of side effects (high levels) and resistance (low levels).

Figure 7: A missed or late dose increases the risk of resistance

Graph showing how a missed or late dose causes drug levels to drop to a level with risk of resistance

Figure 8: Types of resistance tests

Genotype tests look to see how the structure of a sample of your HIV may have changed. Phenotype tests see whether HIV drugs still work to control your type of HIV.

Figure 9. Using only one active drug will only work for a short time

Graph showing viral load increasing overall from just below 50c/mL to over 5,000c/mL, with logs drops (1-2) not lowering viral load sufficiently.

Figure 10: Waiting to use three new drugs is more likely to get viral load undetectable

Why a combination can fail

1) Adherence.You might have missed doses or not understood how important this was. Your doctor is likely to talk about adherence first.Be as accurate as you can about this.If you did not miss doses it is important that your doctor believes you. Ask questions about treatment until you are happy with the answers. Talk to your doctor, health advisors and friends.Read community leaflets and websites. Take control of your own health. Ask for help if you need it.
2) Taking meds with or without food. Some drugs need to be taken with food and others without food to reach the right levels. Check that you had the right information. Not following this advice might mean you were only getting only half the dose.
3) Low drug levels. You were taking your drugs on time but they were not absorbed properly. Some people absorb low drug levels.This is less common with modern meds but may still be worth checking.. Drug levels can be checked for some drugs. These include PIs, NNRTIs, integrase inhibitors, maraviroc and T-20.
4) Drug resistance before treatment. Resistance might have been missed before you started. Even taking all your meds on time can’t overcome drug resistance. Get a new resistance test and an expert review of previous tests.This will help chose your next drugs.
5) If your combination had side effects. No matter how good your combination is on paper, if you have difficult side effects, or it is too difficult to take, then ask your doctor if there are other options. Use new drugs that are still likely to be active.If side effects were a reason for missing doses, it is important that your doctor knows this.There are likely to be other meds you can use.
6) Drug interactions may have reduced the drug levels of your HIV drugs. Other medications, supplements or herbs can interact with HIV drugs.This includes meds you can buy over the counter without a prescription.It can include vitamins and minerals and some recreational drugs.

Your HIV doctor and pharmacist need to know about all your drugs and supplements. This is to check for potential interactions.


7) The drugs in your last combinations. Some drugs are not recommended at high viral loads.

Check that the drugs in your last combination were right for your viral load.

Table 1: Log scales (a log 10 scale is a multiple of a factor of 10).

1 log = 10 1.5 log = 30 1.7 log = 50
2 log = 100 2.5 log = 300 2.7 log = 500
3 log = 1,000 3.5 log = 3,000 3.7 log = 5,000
4 log = 10,000 4.5 log = 30,000 4.7 log = 50,000

Last updated: 1 August 2021.