Isoniazid - High dose (Hh)

On this page

Update: November 2022

Weight (kg)	Daily dose (mg)	300 mg tablet	100 mg tablet
5	75-100	−	1 tab
6	90-120	−	1 tab
7	105-140	−	1½ tab
8	120-160	−	1½ tab
9	135-180	−	1½ tab
10	150-200	−	2 tab
11	165-220	−	2 tab
12	180-240	−	2 tab
13	195-260	−	2 tab
14	210-280	−	2 tab
15	225-300	−	3 tab
16	240-320	−	3 tab
17	255-340	−	3 tab
18	270-360	−	3 tab
19	285-380	−	3 tab
20	300-400	−	3 tab
21	315-420	−	4 tab
22	330-440	−	4 tab
23	345-460	−	4 tab
24	360-480	−	4 tab
25	375-500	−	4 tab
26	390-520	−	4 tab
27	405-540	−	4 tab
28	420-560	−	4½ tab
29	435-580	−	4½ tab

30-35	450	1½ tab	−
36-45	450	1½ tab	−
46-55	600	2 tab	−
56-70	600	2 tab	−
> 70	600	2 tab	−

Alternatively, 50 mg dispersible tablets may be used instead of ½ tablets of 100 mg.

Do not administer to patients with severe hepatic impairment.
May cause:
- peripheral neuropathy;
- hepatotoxicity;
- hypersensitivity reactions, arthragias, optic neuritis, psychotic reactions, seizures and depression.
Monitor closely:
- pregnant and breastfeeding women; patients with renal impairment, diabetes, malnutrition or HIV infection (increased risk of neuropathy);
- patients with alcohol dependence (increased risk of neuropathy and hepatotoxicity);
- patients with chronic hepatic disease or taking rifampicin or ≥ 35 years (increased risk of hepatotoxicity);
- patients taking antiseizure medications, benzodiazepines (risk of toxicity), warfarin (risk of bleeding). Dose adjustment may be required.
Avoid or monitor combination with cycloserine or terizidone and thionamides (increased risk of neurotoxicity).
For the management of adverse effects, see Appendix 17.
Administer concomitantly pyridoxine (vitamin B₆): child: 1 to 2 mg/kg (usual range: 10 to 50 mg) once daily; adult: 100 mg once daily.
Pregnancy and breastfeeding: no contra-indication. Administer pyridoxine to the mother (as above). Observe the breast-fed neonate or infant for adverse effects and supplement it with pyridoxine (1 to 2 mg/kg once daily).

–

– Below 25 °C